Michael and Susan quickly tired of a weekend alone, the two kids capering about the house, playing games, going into the backyard, then sitting around in the kitchen being bored. Mike’s penis started getting tickly, because that’s… just what happened to him now. He felt his scrotum shifting mysteriously inside his underwear, and couldn’t help but recall the last time he orgasmed.

Mike had been ejaculating more and more as the year had passed. His penis had grown from a pencilly little thing to a powerful thick monster, from his perspective at least. He still had a good way to go before becoming an adult, but the 12 year old boy could grab his whole hand around it when he was erect.

The first time he got an erection and started touching it, he’d been scared. He was still scared. He couldn’t believe he was this… boy who was supposed to put babies into a girl. He and Susan were both pretty well educated on that. So a 10 year old Michael had been stroking his stiff little penis wide-eyed, feeling it tingle more and more, not believing that he was gonna orgasm and climax just as the book had said.

When it took him, he panted desperately, arching up as if to thrust into a girl, and his penis just started jerking with strong bursts of pleasure, instead of feeling like his whole body was just continuously electrified. He watched himself pumping, trying to put his semen into a girl, even though he didn’t have any semen yet.

His penis wasn’t tingly after that, and he didn’t do it for a while, until a week later when he got an erection in bed. That time, he… thought about putting it in a girl more. He’d seen girls. His father had showed him diagrams at least, of how a penis goes into something called a vagina. Every time his little pecker got erect, he’d think about the girls he’d seen more and more, wondering what it would feel like when he did it to them.

He was trying to find a girl to have sex with before he started ejaculating, but one day he’d been hunched over in his bedroom, and a little bit of milky liquid started spurting out. It was all over after that. He didn’t wanna actually make a girl pregnant. He started ejaculating more and more, until he was quivering there, ejecting strong spurts of virile semen that just fell to the floor. He had to start using tissues to catch it, and… his penis only got bigger from there.

Michael really didn’t want to ejaculate into a girl, so the fact that he couldn’t stop those strong ejaculations should have dissuaded him. But they just drove him wild instead. He started spurting intentionally, trying to get it into a girl, an imaginary girl at least. Michael couldn’t do it on demand, but he could rush himself urgently to climax, wanting more and more to spurt, and thinking more and more about putting his penis in a girl, and making her pregnant.

Susan hadn’t had nearly as aggressive a sexual awakening. She started getting her period at 12, which sucked, but it made her think about what could be done down there. She started putting things into herself down there. Not climaxing, just feeling what it was like to have something slide into her deeply, imagining if it was a boy’s penis. She couldn’t let a penis in there, because those things started spurting, and then she’d be pregnant.

But Susan’s first orgasm was touching herself, one hand on her smooth, flat belly, imagining it getting huge and tight, imagining it flexing powerfully to push a baby through her vagina. Every orgasm seemed to make her want it more. It made her think about it more. It made her… look at boys. Their enigmatic pants, under which was the penis that was going to impregnate her. It felt… deliciously dangerous. She’d fantasize about them taking her, and put something deep inside herself, unable to decide just which boy would do it, but trying to imagine him sliding in and out. Susan started getting so wet, that she couldn’t help but wish a boy would fuck her, just so he could feel that slick heat between her legs.

So she and Mike had a class together, and did a class project together. And they played together after that, because Mike was nice, but also for that tantalizing prospect of the penis hidden in his groin. She couldn’t… just go and get pregnant, but she could enjoy the proximity to a boy who could do her.

She looked up when Mike stood up to leave. “Going to the bathroom,” Mike said dismissively, then the boy strode into his house’s bathroom and shut the door. Susan snuck up to it, eager to hear him peeing like a boy. She liked hearing that strong stream hitting the water of the toilet, because it reminded her of how boys were different than her, and of what their penises could do to her.

She didn’t hear the stream though. She got confused, until she heard Mike’s heavy breathing in there. Was he…?

“Susan…” Mike moaned quietly. He was! He was masturbating!

She could hear it now, his urgent grunts and hard panting. He… he said her name! Susan shouldn’t say anything. But if she didn’t then he’d orgasm, and not want to try it with her!

So Susan knocked on the door. Expectantly, Mike froze. Quiet in there, he called out, “Yeah? Almost done.”

“Mike, I could hear you,” Susan called back, “You can… go ahead and do it. I just wanted you to know I heard you.”

There was a pause, and Mike was at the other side of the door than, saying muffled, “I–I–I didn’t mean you, Susan. I was just thinking a-about…”

“It’s natural!” she protested, “Go ahead a-and think about me. Just… you know, do your boy thing.”

Mike was not gonna do his boy thing now, because he had been aching and groaning and yearning to just jam it into his friend more and more as he touched himself. He pulled up his pants, then opened the door to find Susan still like right there.

“I… I didn’t wanna finish yet,” he said faintly, “It’s a… a guy thing.”

“You were saying my name,” Susan said neutrally, and oh wow she could even smell him. He could smell her too, big time, but didn’t realize that the heady scent of her moist loins was getting into his head. “Do you… wanna do it with me?”

“Well I uh… I mean we don’t have to, I just…” Mike said sheepishly, the boy blushing and backing up a step.

“No, no it’s okay, i-if you want it,” she said cautiously, “I’m curious—I mean I’m curious how boys feel about that sort of… stuff.”

“You wanna talk about it?” Mike asked, “I’m curious about… girl stuff, too.”

So they sat on the couch and talked about it, growing increasingly comfortable with doing so. “So my… it just tingles sometimes, and then I have to do it,” Mike said unsurely, “It’s been getting… bigger, and… and I started ejaculating.”

A thrill went through Susan at that. She wasn’t on her period right now. She didn’t even have a tampon in there. Nothing but her pants and panties stopping him from impregnating her. “Do you ever… have to touch it?” Mike asked.

Shaking her head, Susan said, “No, not really.” As Mike deflated in shame, she added, “I still… do it. A-and when I orgasm, I think about… boys putting it inside. Do you want to… put your penis inside me?”

“I… I do,” Mike said cautiously. “But I don’t wanna get you pregnant.”

“Well, I’m curious though,” Susan said in frustration, “How you feel in there. You don’t have to make me pregnant. Just… you know, put your penis inside me.”

A moment’s thought, and Mike said, “Okay, if you want. I mean I–I’m curious too. Just to feel what it’s like inside… you.”

Susan blushed at that, frowned, and said seriously, “Okay let’s try it. Just… upstairs on your bed, okay? I just want to see how it feels for you. Don’t want to go all the way.”

“Okay, if you’re… okay with that,” Mike said giving her a wary look.

“Are you?” she replied challengingly, “I’m just as old as you, so I feel the same way you do, just without a penis.”

“Of course I’m okay with it!” Mike said, “I just want to make sure you’re… you know what let’s just do it.”

“You took the words out of my mouth,” Susan purred, in devilish pleasure.

Up in Mike’s room, Susan sat on his bed saying, “So I guess I lay like… this? And you get on top of me?”

“Not with your pants on!” Mike declared in semi-amusement.

Biting her lip, Susan said, “…you first.”

“Okay, fine,” Mike said blushingly, “B-but I’m erect, because… because I’m about to put it in you, and it’s just… just so you know.”

He pulled down his pants then, revealing briefs barely holding a sizeable bulge. Pulling them down, his cock bounced out stiffly, bobbing in the air as they both took in the fact that Mike’s very slightly hairy crotch was exposed.

He finished pulling down his pants, while Susan took off hers. Struggling her panties off, she blushed and said, “So yeah I don’t have a-a penis or anything.”

“I can really go in there?” he asked, looking as the velvety V between Susan’s legs with fascination.

Susan felt like she was melting from the waist down, looking at that thick, hard penis jutting out from Mike’s pelvis. Was that normal sized? Would it hurt? She wanted it so bad.

Laying down, Susan said, “Yeah, just… climb on and see if we can do it. I… I put stuff inside me before, so I think you can do it.”

“Just uh, let me know if I’m hurting you,” Mike said uncertainly, climbing onto the bed, just staring in amazement at the wrinkly cleft in Susan’s smooth groin. His dick throbbed at the sight of where he was gonna really put it. He wanted it so bad.

Mike straddled Susan’s legs at first, but Susan pulled her legs out, straddling him instead, upside down. The squirming teens both stiffened as Mike let go of his penis and it just smacked down on Susan’s mound.

“Well… t-there I am,” Susan said in nervous humor, “You can probably figure it out. H-how do I feel?”

“Y-you feel soft,” Mike said dumbly, staring at his penis laying against her pelvis, “I can really just… put it inside you?”

“Why don’t you try and find out?” Susan said teasingly, unsure of whether to wrap her hands around his back or not.

Mike pressed against her, the thick head of his penis feeling around there, and then he slid inside her. Susan cried out as his penis stretched her open, a little wider even than the dildo her parents had got her. “Are you… okay?” Mike asked, flushed, as he guided his penis into her.

“Y-you’re inside me!” Susan said urgently, “I wanted a boy inside me so bad. The dildo I wanted a penis I I unhhh!”

“My penis… needs to go inside you,” Mike said panting as the urges rose in him, “It’s just surging up in me… I… I wannit.”

Mike’s hand left his penis, as they both gasped when it stayed embedded inside Susan. Mike braced his hands on either side of her and they both stared in fascination as Mike pushed his hips urgently against hers, his penis vanishing into her hips, as it entered her hot, moist, clinging tunnel.

“S-susan you’re hot inside! You’re h-hot!”, Mike stammered as his hips came to press down hard against Susan’s, getting another urgent cry from her,

“Mike you’re—ahh!”

“We’re doing it!” Mike said, rocking his hips a little despite himself, “That’s my penis! I I wanted to do this, want it in your vagina.”

“Mike Mike it’s… it’s stretching me!” Susan declared urgently, touching her straining mound as she felt him flex inside her, “I feel your… your penis! It’s so deep and… and soft! I… I feel like I’m holding it, in my hips. W-with my vagina. I’m holding it!”

“Feels so good…” Mike moaned, grinding against her, “I never want to leave. I… I want to ejaculate inside you.”

“You’ll make me pregnant!” Susan hissed urgently, the girl feeling stuffed, and stuffed with a living thing that was twitching in there. She touched her belly, trying to feel where it was inside her.

Mike panted heavily, the boy holding still, pelvis square up against hers, penis in an oven of wet flesh. He didn’t want to take it out. She wouldn’t let him in again if he took it out, and she’d be right, because he wanted to impregnate her. “I’m… different now,” Mike said shakily, “My penis started making me want to… impregnate girls. It–it squirts out of me, and every time I do I want to… to be inside you.”

She tensed as he pulled out, and pushed in again, grinding his hips against hers, twitching in there. “I-I’m different now, Susan,” he repeated quietly, “I’m going to i-impregnate you. Didn’t want to tell you until I was inside. But now I am, and I’m… gonna do it.”

Mike started sliding in and out, just to show her, but he needed to as well. “You’re different too,” he said intensely, “You want me to… to cum inside. Because you’re a girl, and your… vagina changed you. You want a boy’s penis to e-ejaculate in there.”

“Mike… I want it so bad,” Susan said, looking at the slow, shaky pumping as his penis slid in and out of her groin, “Want boys to do… this. A-are we gonna have a baby?”

Thrusting a little faster, Mike started panting, murmuring, “I’m gonna put a baby in you… with my penis.”

“Mike, you’re sliding!” Susan squealed, bracing against her bed as he had actual sex with her, “It feels so… sliding all along my… vagina. Need you innn!”

She grabbed her arms around him then as Mike urgently fucked her, thrusting in and out with a mindless rhythm, his young penis still needing to put his sperm into her. The boy pushed deep then, and held it, throbbing achingly.

“Are you… doing it?!” Susan gasped, looking up at him.

“I want this… to last… forever,” Mike said desperately, pushing up from her even as his pelvis kept that penis deep. “Can’t… can’t keep going after I ejaculated. I-I’m gonna… cum inside you.”

“I’ll let you do this again and again until I’m pushing your baby out. Any time you want,” Susan said, trying to deal with what she was right now, “Mike, I… I started needing a boy to ejaculate right in there. I touched myself and…” Susan’s fingers trailed down to her labia, stretched tightly around Mike’s straining shaft, “You’re there, Mike. I’m turning into a… a girl,” she huffed intensely, her cunt pulsing tightly around him, “A girl who needs you in. Can’t stop making your baby.”

“S-susan, we shouldn’t,” Mike said, trembling as he fought not to thrust.

“Yeah,” Susan wanly replied, touching him where he stretched her, “You’re getting ready to, though.” Gently cupping at his balls, Susan said, “S-so these are… where your sperm are. You’re getting ready to squirt them from these, into… me. C-can you feel them getting ready to …squirt?”

“Yeah,” Mike said lowly, “They move on their own. They’re moving to… to get ready to squirt I guess.”

She felt fascinated at his sack as his scrotum shifted delicately against her fingers. She pulled her hand back as Mike retreated from her attentions, but to the feel of her racing heartbeat, Mike was just pulling out. Susan panted desperately, saying, “It feels… it feels… Mike you’re sliding out of me! Pulling! Mike!”

He pushed hard, and Susan whimpered, as her desire flared even more. Clinging to his back now, she and he both urgently declared, “Nnf!” as their hips collided again.

“You’re all around me,” Mike said headily, “You’re so hot and… wet. I… I wanna squirt every drop… into you.”

Mike started pulling out and pushing in again. He knew what he was doing. He was gonna put a baby into Susan. He was gonna ejaculate as hard as he could. And he still did it. Just like the books. In and out, in and out.

Susan didn’t complain one bit, at all. She just panted and sweated, and stopped looking at her penis engulfing groin to look up at him. He looked at her as Susan said breathlessly, “I… I don’t need to look, because I can feel you… doing it!”

Mike’s mouth dropped slightly open as he panted there, thrusting faster and faster, until Susan couldn’t even think from the unstopping rushing tingles just exploding inside her. “Push in!“ she urged desperately, “Push—!”

He pushed deep, and Susan bucked against him, writhing underneath him, staring up at him in ecstasy and fear, hoping he didn’t mind her… her orgasming first. “I swear this… never…” she said through gritted teeth as he started thrusting gently, “I can’t stop it—it squeezes. Just let me… oh oh oh I I I hnnnhh!”

She orgasmed like a whipcrack, shocked at how it hit her, just saying, “I—ungk!” Her whole cunt started pulsing with rushing tingles then. She twitched there like a maniac, staring up at him in embarassment, but at the same time not caring. Her eyes slid half closed, as the rushes of pleasure just changed her. He held deep inside her, until every… clench… stopped.

Then he started fucking her again. Her hands were getting sweaty against his back. He was inside her. He was sliding inside her, just the way that was gonna get him to cum! Mike felt it building up inside him, and didn’t even hesitate. He pinned Susan down under him, fucking her urgently, determined to feel every hot spurt from his penis fire up inside her.

He fucked and fucked, and he felt himself orgasming and he couldn’t stop it! It wasn’t an effort like this. Not like his hand. Now he ached to be inside a girl, and he was. The need to impregnate her was overwhelming, and he climaxed so effortlessly. His penis knew exactly where it was. Gritting his teeth, Mike pushed deep and said, “It sort of—” and then spurted hotly into Susan.

“Hnh! Hnh! Hnh! Hnh!” was all Mike could say as he held her down and pumped spurt after spurt of virile semen into her.

“Oh yesss,” Susan moaned, squeezing her legs around his ejaculating butt, feeling hot splatters of cum smearing deeper in her than she could imagine. “You’re changing me Mike,” she growled as his cum settled quiescently inside her and prepared her for entering pregnancy. “I’m getting pregnant now.”

Her clitoris was practically smooshed with how she had to stretch around his penis, and she attacked it with her finger, her own lubrication slipping slimily all over it. “I’m… I’m just a girl,” she panted frantically to the relaxingly concerned Mike, “And you came… inside me! Have to… give birth now! I wannit I wannit I wannit—!”

His finger came to touch hopefully at where she was rubbing, and as soon as he pressed into her clitoris, Susan winced from the tense unstoppable orgasm, whining, “Nnnnn…nnnnNNH!!”

Then her head fell back to Mike’s bed, her eyes staring at nothing as she orgasmed even harder the second time. Bucking up against him spasmodically, flexing powerfully around his penis, all Susan could do was gasp and… and Mike kissed her. He pulled her head up and pressed his lips to hers.

Susan grabbed him like a vice, groaning into his lips, the rushing tingles through her whole body flooding her with waves of pleasure, the hot, primal clenches of her nethers around a penis that really was in there, and cum was in deeper, making her pregnant. She hugged him close, and gratefully shuddered there. He held her while her vagina pulsed and pulsed, and her whole body spasmed with it, and it was okay, because she could do this, and he loved it.

“Thank… thank you,” Susan whispered at last, hardly daring to move, “I c-cum like that and you… I know you love it, because you’re a boy, but t-thanks for letting me just… ohhh it feels so good!”

“I… I didn’t mean to put a baby in you,” Mike said anxiously, “I–I did though. I was trying so hard to put a baby in you. My penis just… takes me over, and makes me want to put babies in girls. I–I didn’t care about you, only about putting a baby into you. S-sorry…”

“You say you’re sorry now,” she said in languid amusement, sinking back to the bed again to gaze up at him, “While your sperm are swimming in me right now. That’s you. You’re still in there, trying to impregnate me. And you can’t stop, until… until it happens.”

“I.. I wanted to put them into you,” Mike said, “When you touched my balls, I… wanted to put sperm into you. I’m… g-glad they’re swimming inside you, and—and that you’re gonna get pregnant now, once they find your… your egg.”

“It might be okay,” Susan said, still breathing hard from that, “As long as we don’t do it again.”

Several hours later, they were doing it again. They stayed naked in the house, and then he just grabbed her from behind and started doing her. Mike got every drop of semen he had into her that weekend, until they were so drunk with the urge to writhe together and breed that they didn’t even care that their lives were going to change.

The best was at school later that week, when Mike said he needed it again, and Susan said she wasn’t wearing any panties under her dress. So she got to hang onto a tree while Mike grabbed her leg and just pulled his fat dick into her vagina. She didn’t care if anyone saw. She wanted to make a baby, and this was sure to do it. She climaxed when Mike pushed deep, and she felt him jerking in there. Her hands tightened on the rough tree bark, and she leaned there against the tree, feeling his hot splatters of semen flooding up into her birth canal.

Mike didn’t care if she had a baby. He had to get inside that sleek, round groin, just shove it in there and feel his semen spurting deep into his friend. His penis was tingling so much as it slid in and out of her. He didn’t say anything, just fucked her. Just grabbed Susan’s leg, and pulled himself into hot, wet ecstasy. He pushed deep, and exhaled hungrily in short huffs as he pumped, firing spurts of semen from his penis up deep inside her vagina. He pushed deep into her and spurted, spurted, spurted, spurted. And if she wasn’t pregnant before, she sure was now.

Then he pulled out and caught her from falling, laying her down on the grass, and then just urgently penetrating her again, even as Susan’s convulsions shook her body. She loved him so much as she felt his penis push into the vagina that she couldn’t stop flexing in orgasm.