It's a lovely afternoon and Smith was happily playing with his toys. 

"Smith, dear?" Natalie called sweetly.
 
"Coming." Smith said. 

Smith went over to where Natalie was. He also saw his grandfather Armen. Natalie smiled when Smith came face to face with her.
 
"Um, what's happening?" Smith asked.

"Smith, I figured since you don't know how sex works, me and your grandmother here are gonna show you the ropes." Armen said.
 
"Now pay attention, Smith and learn." Natalie said.

"Alright." Smith said, opening his ears*

"Now, for us to reproduce, there's these little parts we all have between our legs called genitals." Armen said. "For boys, we have penises, and for girls, they have vaginas. Both of those things are required for reproduction."
 
"Grown-ups call a penis either a 'cock' or a 'dick'. A vagina is also called a 'cunt' or a 'pussy'. It's where babies come out of." Natalie said.

"As for the process itself, you'll know when you're ready to go at it when something happens." Armen said. "For boys, his penis goes erect and for girls, her vagina goes moist. I believe you've had that happen to you, Smith."

"Well, I did feel my wee wee stand up on its own a couple of times." Smith said, shyly.

"How does it feel?" Natalie asked.

"It felt kinda weird." Smith said. "Is there more to that?"

"Yes. There is." Armen told Smith. "While your penis is erect, once stimulated enough, you can make it shoot out a special white sticky substance."

"Huh? White substance?" Smith asked, confused. "Is it pee?"
 
"You'll see." Natalie said.

Soon, Natalie starts stroking Smith's cock.. Smith moans from the stroking.

"Okay, this feels a little weird, but kind of good…" Smith said in between moans.

Natalie smiles and gradually went faster while fondling his balls. Smith moans as his little dick gets stiff from the rubbing.

"My pee pee's stiff again…" Smith said, moaning.

Natalie kept pace as she stimulated her grandson's penis.

"You didn't tell me that this was fun." Smith said.

"It is." Armen said. "Well, at first, it feels odd, but sooner or later, you'll feel like a new man."

'Cum for grandmother, baby!' Natalie though as she felt her grandson's member pulsing as he is about to cum.

"Ah... It feels like I have to pee…" Smith said.

"Not quite, but let it out, sweetie!" Natalie said.

Smith moans as he cums an entire load. A little strange considering how he is a little kid, and boys his age would very much have dry orgasms. Smith shouts in joy as he came hard shooting his hot, thick and creamy cum. A minute later, his climax ends.

"That was...amazing…" Smith said, panting and recovering from his climax. "What exactly was that?"

"That, my grandson, was an orgasm." Armen told Smith. "After a certain amount of time, you'll eventually reach that stage. For boys, the satisfaction comes from one orgasm, as for girls, they have multiple orgasms."

"And this sticky white stuff is called 'semen' or 'cum'." Natalie said. "I made you cum."

"Does everyone make this cum?" Smith asked.

"Nah, just boys." Armen said. "And sometimes, cum comes in a variety of tastes. The taste is usually bitter, but it can change depending on what you eat."

"That was lovely." Smith said.

"Now, let's see you try it out with an actual girl." Armen said. "Natalie, can you get Milly, please?"

"All right." Natalie said before she calls out for Milly. "Milly, dear?"

"Coming, mommy." Milly said, as she walks to where Armen, Natalie, and Smith are.

"Would you like to help us teach Smith about sexual intercourse?" Natalie asked.

"I'd love to, Mommy." Milly said to Natalie. "Now, you might be nervous at first, but ease yourself first." Milly said to Smith.

Milly then takes off her panties and presents her pussy to Smith.

"You see that, Smith?" Armen said to Smith. "When a woman or girl shows her vagina to you, it means she wants you inside of her. Now go ahead."

"Well, okay." Smith said. 

He slides his dick inside Milly's pussy, making her moan a bit.

"Yeah... Good job." Milly said. "You did it right."

"Now, what exactly do I do now?" Smith asked.

"Oh, Milly!" Natalie said to Milly. "You look SO beautiful and sexy naked or with clothes on!"

"You just gotta slide your pee pee in and out until you start to fill me with the white goo." Milly said. "Got that?"

"Oh... Okay…" Smith said before he starts fucking Milly.

"Yeah." Milly said. "Just like my twin brother!"

Smith continues fucking Milly, and slowly increases his speed.

"I sure wish Lucas was here to see this." Armen said. "I'll go get him right now."

Armen goes to get Lucas and brings him to Natalie, Milly, and Smith.

"What did you bring me here for, daddy?" Lucas asked.

"It's Smith. Milly said to Lucas. "We're teaching him on sex."

Smith fucks faster, being careful not to rip apart Milly's pussy.

"I can't stop!" Smith said on the brink of an orgasm. "I'm about to...cum again…"

"Do it." Milly said.

Smith cums inside of Leika, and then pulls out of her.

"Oh, wow. That felt amazing." Smith said. "Is this what you and grandpa do, grandma?"

"Yes, dear." Natalie said. "This is called "Sexual Intercourse"."

"And the best part about it is you can pretty much perform it with anyone however you want, depending on your sexuality." Milly said. "If you have any more questions, come to us or ask mommy or daddy."

Milly as well as Lucas walk back downstairs.

"That was a lot of fun, grandma and grandpa." Smith said.

"We're glad you like it, love!" Natalie said to his grandson.