The package landed with a thud at the doorstep. It wasn't even seconds later that the house’s owner showed up to take it and hurry back inside. The snow leopard walked with a spring in his step and a sway in his tail. After a whole agonizing week of waiting the undies he'd ordered were here. Ryan could barely contain his excitement as he used a claw to cut the tape away.

Inside was a pair of navy blue, Aussiebum briefs. Emblazoned big bold letters right across the waistband was AUSSIEBUM. He had to suppress a giggle just looking at it in his hands.

Even better though was the particular type he'd bought. This company also had a brand called “Enlarge It.” It was a type of undies specifically designed to… well, do just what it's name suggested. Enlarge the bulge of the wearer. The undies sported a large pouch on the front to hold the wearer's package, kept just tight enough to accentuate their goods. Ryan grinned. Some extra heft to his bulge would be nice. A lot of extra heft would be even better. They weren't designed to do the sort of enlarging that he'd prefer from this sort of underwear, but it was still too perfect to pass up.

Once the navy fabric was sitting comfortably on his spotted hips, Ryan made his way over to a full body mirror. He wanted to get a better look at how they fit. The smiling snow leopard there looked mighty handsome in the briefs. They were certainly comfortable to wear too. The pocket fit his goods just right and the soft fabric hugged his rear enough to show off a bit. Ryan turned around to get a better look while his big fluffy tail swung back and forth. Mmhmm. Looking good from the back.

But despite the positives it was still something of a let down. The Enlarge It didn't affect much in the size department. It couldn't actually make his package larger but it was supposed to look that way; he cupped his groin in a palm and sighed. Just the same size as always.

Maybe there were instructions or something. Ryan didn't want to believe he'd spent money on it for nothing. It could be he was wearing them wrong or something. Just as he was about to turn and leave he noticed a tingling sensation right beneath his sack. Confused, he turned back to the mirror. The briefs looked a little off center. With an adjustment Ryan wrote it off as nothing to think about.

Until he noticed that his thighs felt a little more crowded than usual. Another light tingle and slosh between his legs signaled that something was definitely going on. The snow leopard pulled at his briefs again. They still fit perfectly well but something felt amiss. The pocket in front felt tighter, fuller. In fact the whole thing felt more snug.

Somehow his bulge looked larger. He couldn't believe it though. The only possibility was a trick of the eye. He wanted the briefs to work so badly it just looked like his junk was larger. The tingling sensation at his crotch was kinda annoying though. That definitely wasn't advertised on the website. Ryan shrugged and went back to his business, satisfied that the Enlarge It briefs had at least made his package look big.

As the minutes passed the tingling feeling didn't go away. He tried to focus on cooking a meal for himself rather than on how good it felt. Aussiebum didn't mention that the briefs would be quite so pleasurable on his nuts but he certainly wasn't complaining. The snep purred while warm, tasty smells flooded the kitchen. It took a good half hour to finish before he was ready to sit down and eat. As soon as Ryan began to sit at the kitchen table he felt a jostling against the front of his thighs.

It only took a look down for him to see what had happened. A grapefruit-sized bulge greeted the snow leopard. He gaped. Was that actually his? He gingerly poked at it, and moaned when tingles of pleasure shot through his groin. Yup, it was definitely real and definitely his. How could this have happened? Enlarge It only made things look bigger, not literally enlarge it! It sloshed against his thighs held easily in place by the taut fabric enclosing it. The briefs didn't seem any less comfortable, despite the obviously larger snow leopard bulge. It looked more like the briefs grew to fit its occupant. No wonder he hadn't noticed right away what was going on. The briefs felt just the same as before.

He knew right then that he should take the briefs off. Something weird was happening. It would be safer to take the Enlarge It briefs off until he could figure this out. He knew that to be true. But his hands didn't take the briefs off. Instead, they reached down to heft his bulge with both palms. It nearly over filled both of them. His feline face turned a shade of pink as he made a decision. No reason to take them off right away without testing it first. He'd have been lying if he didn't admit to being curious.

Ryan spent a good hour simply testing out his new package. Posing in the mirror for pictures wasted a good bit of time. So did lifting it, toying with it, and rubbing it. His balls sloshed in his palms pleasantly. He purred with each movement but never went further than teasing himself. He wasn't willing to do anything more than that for fear of making a mess with his new clothing. They continued to bloat with each passing minute; he only noticed the change in size when he took another picture at the end.

Comparing the size change over an hour was enough to pull the snow leopard away from his fun. The meal he prepared languished on the table, completely cold now. What a shame. That meant he would need to go out to get some food. And that meant finding some clothes to put on. Ryan looked down at his junk, football sized now and still expanding. Can't go out in undies only, but way too large to fit normal pants now.

Sweatpants it is.

Surprisingly the setup was pretty comfortable. Even if he did look a little strange with the pants stretched out that far. The trip out would be quick, so there wasn't any need to worry about stretching them much more. A fast food run, then back home to figure out what to do. No problem, right?

The workers at the drive through didn’t seem to think anything strange of the bulge resting heavily in Ryan’s lap. Either they didn’t notice it or thought it had to be something else; who could imagine a snow leopard with a jumbo watermelon sized bulge after all? It was only properly watermelon sized by the time he got home though. The traffic getting there and back had been awful. Traffic jams both ways, nearly an hour for the whole trip. Annoying for sure, but it did give him some more time to look down on occasion and marvel at the fact what was between his legs actually did belong to him. He purred practically the whole way. The light throbbing held in check by his comfy cosy briefs was starting to cover his thighs and pin them in place. It felt warm, like having a large sloshing pillow in his lap. The extra weight tended to roll to the left or right with each turn throwing off his usual inertia while sitting. That could take some getting used to.

Once home he dropped the food off on the table and sighed, hefting his package up with both hands inside the sweatpants. He was rapidly approaching the size that he’d want to stop at. For now at least. Sure it would be fun to spend the occasional day at an even larger size. Filling the space between his legs, or spilling over his bed with a couch sized bulge. But definitely not for long term. Having something a little larger than normal, like football or basketball size was absolutely the way to go. Something to cuddle with, maybe even show off a bit with some nice looking undies. But he wanted to still be able to live normally. Ryan pulled out the box his undies came in looking for instructions. There had to be something about shrinking back to normal, or shrinking a little bit.

As he did, the cardboard box bumped into his water cup at the edge of the table. The liquid fell out and splashed off the side of the table, getting the snow leopard all wet. From his torso down the water dripped, and Ryan grabbed at the knocked over cup to set it upright with cat-like reflexes. Shoot, now his fur was all wet. He’d need a towel, brush and hairdryer to get back to full fluff potential-

A deep warming sensation overtook his crotch suddenly. This was nothing like the slight annoyance of a tingling sensation he’d gotten used to. It felt like a heater was turned up and faced directly at his crotch. It didn’t hurt but it was much different. He pulled out the waistband of his sweatpants to take a look at what was going on. His hips buckled suddenly as a good foot of size was added to his junk, held nice and snug inside the Aussiebums.

That wasn’t supposed to happen! The feline’s eyes widened as his bulge expanded dramatically, surging in size. The growth came in bursts of nearly a foot at a time, one right after another. What was only reaching down to his thighs a second earlier was now to his knees. With another burst it was past his knees. Ryan squeaked in surprise, looking around for the instructions again. Something was going terribly wrong with his briefs; he figured it must be something to do with the water he spilled. Maybe they weren’t meant to get wet while being worn.

That info wasn’t doing him much good now, as his bulge flooded in size. It wobbled and sloshed with each explosive round of growth. The sweatpants around his hips struggled as its cargo suddenly went to beanbag chair size. Even as stretchy as it was meant to be the sweatpants were soon pulled taut, and began to rip along the waistband. The elastic pulled away with a snap, letting the rest of the fabric fall to the floor around his paws. Freed from one piece of clothing holding it in his bulge flopped forward a bit before his briefs caught the slack and held it up. The snow leopard was almost pulled to the floor by the sudden movement.

Nope, this was no good. He needed to do something before it got any worse than this. He tore through the package, struggling to ignore the feeling of his briefs bulging forward, pressing down on the top of his feet. It didn’t look like there was anything in the box… wait. A small piece of paper fluttered out and landed on top of the quivering, navy blue fabric of his Enlarge Its. He snagged it and scanned the words, looking for any sort of instructions. Generic hello, thank you for buying our briefs, we hope you enjoy it, blah blah blah. There, finally at the bottom was something about returning to normal size.

“When you are satisfied with the size your Enlarge It AUSSIEBUM briefs has given you, simply take them off. You will begin to shrink back to your usual size over the course of a few hours. Enlarge It AUSSIEBUM briefs are dry clean only. Do not attempt to wear if wet. For Customer Service, please call-”

The snow leopard couldn’t read any further than that. His focus was taken away when he felt something push into him from in front. In fact, it looked like the kitchen table was being forced away by the explosive bouts of growth his bulge was undergoing. Ryan moaned and rubbed gingerly across the sensitive flesh. His package was still enlarging at breakneck pace, one foot added, two, three. It pressed up against the kitchen counter on one side of the room and started to spill over top. The room wasn’t going to last long if he couldn’t get this under control. It was easily taller than the whole of his body, and pushed out much further in front too. Maybe if he could just work his undies the right way it could come off.

Forcing himself to focus on the task at hand rather than the pleasurable feeling of filling up an entire room with his junk, he pulled at the Enlarge It waistband with all his might. But it didn’t budge, not even a single inch. There wasn’t enough slack in his undies anymore for it to come off. Ryan’s eyes widened; that wasn’t a good sign at all. He tried to scoot backward, to find somewhere to sit and get a little more purchase on his bulge. But he found it difficult to maneuver with his bulge easily outclassing him in weight and size.

The snow leopard mewled, trying to pull himself together and fix the problem. But it felt… really good. If he couldn’t get the fabric off now who knew just how large the briefs would make him. It was too tempting to just lay across his bulge though, hugging into it and rubbing. From around the sides and front he could hear glasses being knocked down and furniture breaking, but he couldn’t see past the navy blue wall of bulge.

Ryan purred and blushed a deep red, feeling the ceiling press into the top of his bulge. It had to be nearly big as a boulder now as it filled all corners of the room in front of him. And worse than that, all the rubbing against his sensitive package was starting to get him going. The stretching inside of his Enlarge It briefs increased yet again as his member twitched to life, growing rock hard but the briefs didn’t give way much more room. Instead they creaked and started to pull down off the top of his package to reveal the pink flesh. Just the smallest peek. It seemed even these undies had a limit to their stretch and he was starting to get close to that point.

The snow leopard grunted, grinding his shaft into the ceiling in a desperate attempt to get any sort of leverage on removing the undies. All he ended up doing was teasing himself even harder, painting a wet spot into his undies. This wasn’t going to end well, but he was a little too turned on to care. Once he was done he could worry about fixing the problem. Which wasn’t going to be too long now as he cried out, gasping. His snow balls tightened and sloshed, prepping for the veritable flood of liquid that would soon come.

Miraculously, the briefs held fast against the torrent of cum. It seemed to be designed to take quite the beating and stretching. They stretched out further across his balls as his shaft surged in side, revealing some of the grey spotted fur inside. The flood of seed dripped down to the floor in small globs but somehow remained mostly inside the briefs. They could barely contain the package within anymore, reaching bus sized and still growing.

Ryan’s head cleared of its lust after a good half minute of climax, resting in a tired heap against the package in front of him. That was insane. It took a moment for him to gather his wits again fully after basking in the afterglow of the craziest climax he’d ever dealt with. He blushed heavily when he looked around at the result, with nearly every corner of available space in the kitchen filled. He’d even been pushed backward slightly by the growth to make more room. He didn’t want to imagine how his walls and windows would look when this was all fixed.

Something was missing from the situation though. He couldn’t feel any warmth against his package anymore. Not even the tingling from earlier. Did that mean he was finished growing? The snow leopard tried to scoot backward only to find he was fairly wedged in place. At least until he got soft again… he blushed, thinking about the mess that could’ve made if not for the briefs. Maybe that’s what had stopped the growth; flooding out the briefs until they couldn’t function any more. It was definitely a possibility, considering it was water in the first place that made them go haywire.

The Enlarge It undies were still holding on though. They’d been stretched to their upper limit, leaving absolutely nothing to the imagination. This was quite the embarrassing situation to be in… but he also couldn’t think of any way to get the undies off. The instructions were pretty clear that they needed to be taken off if he wanted to shrink back down. Alone though that would be impossible. Maybe he needed to ask a friend for help? His cheeks flushed an even brighter red at the very thought. But there didn’t seem to be any way around it. So… who among his friends did he trust most to help?

This was going to be a very strange evening.