Silly Non-Prewritten Inflatey Stuff

You're much too small for my tastes, dear. But we'll fix that soon enough!"
>you would respond, except for one thing
>your lips are clamped shut by a leather strap around your jaws, holding a metal nozzle between your teeth
>you don't know why you agreed to this
>maybe you just wanted to test the limits of your cartoon pony body
>maybe it was morbid curiosity
>or maybe your kinky friend was just too persuasive
>your ears perk up at the first high-pitched squeaks of the turning valve
>the cool rush of air fills your cheeks comically
>you hear your friend giggle and feel her hoof as it playfully pokes your body
>the flow finds its way down your throat, not even needing you to swallow
>you're grateful that, at least for now, it isn't overwhelmingly fast
>you both look down to gauge your progress
>sure enough, a small bulge had formed, your stomach looking like it's carrying around a large meal
>she prods it and grins as it gives a few millimeters to her hoof
"See? I knew you'd look cuter with a little belly on you!"
>your cheeks gets hotter, though you're not sure if it's because of they're stretched from the air or if you're actually blushing
>she provides a few sensuous rubs along the swollen curve
>even at a small size, your stretched skin tingles and shudders at her touch
>unable to control yourself, you lean your head back as a muffled moan escapes your throat
>your cock prods and rubs against the underside of your taut stomach as it unsheathes
>it's tantalizingly out of your reach, your forelegs incapable of stretching that low in your position
>but she's not at all oblivious to your enjoyment
>a seductive look crosses her face as she slowly returns her grip to the valve
>she leans onto you with the joint of her foreleg pressed on your navel
>her body weight gently displaces the air to your sides
>a few more twists of the valve open up the flow even more
"You're moving along perfectly, dear! But let's see how far we can take this, hm?"
>fssss

>the mare doesn't waste much time in speeding up your growth
>the way her body leans against yours, it wouldn't be long before she could easily lay on top of your belly
>you don't know how, but you stretch out far wider and taller than you would expect
>you must have gained 50 cm around in your waist's circumference already
>and the tank's supply wasn't even close to being empty
>wider and wider still, your stomach spills out over your lap and forces you to spread your hindlegs apart
>with each passing second it grows out, it grinds against your sensitive nethers
>fully erect and throbbing, but the tension alone is the only force able to stimulate you as your cock is lost beneath the massive ball gut
>before you even know it, your belly alone isn't even enough to sustain the rapid onslaught of air
>it fills out your chest until all you could see was a round expanse of your pastel-colored coat
>it causes your neck to thicken until it resembles a tire, burying your lower jaw as it swells beneath your head
>you could sense that you were more elevated in your seated position, for each rump cheek had become its own air cushion supporting you from below
>you lose function of your limbs and extremities as they stiffen and stick straight out from the pressure
>you could swear the upper portion of your limbs were even consuming your hooves
>not even your cock and balls are safe as they balloon in kind
>a pang of both panic and pleasure surges, making you tremble in wrenching near-orgasm that would cause you to curl your hooves if you could
>your body loses balance and tilts back, teetering into a prone position
>your heart beats as you realize your shaft lies in her line of sight, creasing your belly's underside with every pulse
>you blush hotly, her cheery tone deepening your shame even further
"My, my! How you've grown."
>she teases you by leaning forward licking the glans, leaving you a moaning mess at her breath's mercy
"But you still have quite a ways to go!"