Well I was inspired by a sketch  jacfox drew of himself swelling after drinking Mentos Cola, and couldn't resist writing a story based on it! Involves pool toy inflation and teasing :3

Jac boldly downs a whole bottle of Mentos Cola in one go, and Indi ensures the pool toy fox swells up huge from it...

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Jac's Mentos Cola Swell
By: IndigoRho

Jac held up an unassuming two-liter of soda, looking it over with a critical eye. The red fox pool toy shook his head in disapproval.

“Mentos Cola? That's gotta be an advertising gimmick, right? Probably just a bit fizzier than normal.” Despite the doubts Jac still handled the bottle with extra care, as if one bad jostle would pop the cap right off.

The wide, midnight-blue cheetah pool toy with him smiled. “The label totally claims a drink of the stuff will puff you up good! But if you think it's lying then maybe you should test some out yourself. Might give me an idea of how much to hand out at the pool toy party later. Wouldn't want to provide too much and have to bust out the repair patches early!”

“Unless someone downs a whole case of those they aren't gonna pop, Indi,” Jac said.

“Then take a sip!” Indi insisted. “What's the worst that could happen?”

Jac wasn't sure why Indi was so eager for him to try the drink out. Though Indi was known for pulling pranks Jac didn't want to come across as afraid of a little thing like novelty soda. He'd just take a quick drink and be done with it.

A familiar hiss and fizzle accompanied opening the bottle, but Jac wasn't sprayed with a geyser of foam. Maybe it wasn't a prank, and Indi only wanted to watch Jac get paranoid over nothing. With most of his worries eased Jac drank. Again nothing terrifying happened.

“I think you got ripped off Indi,” Jac said with a sneer. I bet I could chug the whole bottle and not so much as creak!”

“Ha, no way!” Indi replied. “You're always a blimp waiting to happen!”

Now emboldened, Jac felt the need to prove himself capable of handling a mere two-liter. Throwing caution to the wind Jac began guzzling the soda, which could be heard splashing about the pool toy's hollow interior. The bottle rapidly drained, Jac drinking the whole thing at once to show off his confidence. Once it was empty he casually tossed the bottle aside, covering up a tiny belch with a puffy paw.

“See? Nothing, just like I—oof—told you.” An odd look came upon Jac's face.

A muffled fizzing noise echoed inside Jac, and he placed both paws on his middle as he felt the faintest build-up of pressure within. By the time he bothered looking down he'd already rounded out noticeably, the pool toy fox now sporting a small belly. Suddenly concerned about side-effects, Jac leaned over to grab the discarded bottle. The small bit of movement disturbed the soda within him enough to prompt a burst of swelling, causing Jac to lose balance and fall on his squeaky butt.

The fall inflated Jac even further, his vinyl hide creaking loudly in protest as it was forcefully stretched in haste. Jac's belly resembled a large beach ball, and was still slowly expanding. His legs and tail had puffed up some as well. Jac tried to remain as still as possible, to keep the swelling at a minimum. He worried that attempting to get back up would only end in him being too huge to stand.

Indi seemed rather pleased with the turn of events. He circled the baffled fox and gave his bloated middle a few teasing pokes, snickering as Jac inflated a little more with each.

“Looks like the soda worked just as advertised.”

“Meep! H-hey, stop that!” Jac tried to swat away Indi's paws, but only managed to swell up in the process.

The fox was starting to get hit with the effects of being bloated. His hide creaked, and the internal pressure made him feel sluggish, like he'd gorged on a huge meal. He considered opening his valve to relieve the pressure and deflate, but by then it was just barely out of reach.

“Ya know Jac, I'm kind of curious to see how big you'd get if you drank a second bottle...” Indi mused aloud.

“Um, I'm good!” Jac replied, resisting the urge to scoot away. “Soda's probably not good for my diet, I should really cut back on it!”

Unfortunately Indi had already grabbed another bottle, opening it as he loomed over Jac. “Nonsense! A pool toy like you could use a bit more width, makes floating easier.” He patted his own round, vinyl belly. “Besides, you've got the perfect built-in soda intake.”

Jac's momentary confusion turned to worry as Indi began loosening the fox's belly valve. There was a small spurt of air and carbonation, though not enough to impact the pressure within him. With surprising agility Indi flipped open Jac's valve and swiftly plugged it with the open end of the two-liter. More Mentos Soda poured into Jac, splashing as it joined the rest and fueling his expansion. He wobbled in frustration but there was simply no way for him to stop the flow.

Jac creaked and squeaked as his middle grew bigger and bigger. His eyelids were heavy, the pool toy suddenly feeling in need of a nap as the pressure intensified steadily. Indi closed his valve with a firm press that squeezed his gut and made Jac alert again, freeing him momentarily from the daze threatening to overtake him.

“Wow Jac, you're even bigger than I am!” Indi teased, making sure to prod the fox a few more times just to bloat him up further. “Bet you'd make a great chair—though I wonder what it'd take to turn you into a proper air mattress fox?”

Jac frowned and shook his head, the pool toy's body creaking in disapproval as well. “I'm big...I'm big enough. No more,” He almost mumbled, struggling to exert himself much while dealing with the overbearing pressure.

“Silly Jac, no one's ever truly big enough!” Indi chuckled.

The cheetah pool toy took a couple steps back, then abruptly leaped into the air. Jac's eyes opened some as he watched Indi go airborne, gaze following him as he landed right in the middle of the fox's middle. The impact of Indi falling onto Jac made his eyes bulge, both from the spike in pressure and the sensation of the soda being wildly splashed around within. In a flash Jac rapidly expanded, swelling in all directions in a cacophony of creaks, hissing, and fizzing.

Jac let out a frantic “meep” before his cheeks and nose puffed up, rounding out along with the rest of his body. His limbs became rigid and bloated, capable of nothing more than wiggling. The sudden increase in pressure hit Jac like a tidal wave and sent him into a deep stupor. His body took on a spherical form, inflated belly rising up towards the ceiling with Indi along for the ride.

Indi realized far too late just how big Jac was about to get, chirping in regret seconds before he smacked into the ceiling, squished firmly between it and the over inflated fox beneath him. He was completely enveloped by Jac's squeaky belly, too thoroughly pinned to move and pressed into a daze himself.

The inflation had only lasted a few seconds, but once Jac's hide stopped stretching and the soda settled he was practically room-filling. His taut vinyl sides had knocked over furniture and bumped into a wall, and even the slightest wobble provoked long, loud creaks. His gaze was utterly unfocused, drifting in random directions and never staring at anything with intent. The pressure was simply too overwhelming for Jac to think straight. Occasionally he'd mumble but for the most part he just groaned, an immobile, over bloated blimp.

For the foreseeable future Jac and Indi both would be stuck, at least until someone finally stumbled upon and deflated them...