>you, your gf and a mutual friend hanging out at your gf's place for a small, low key get together kind of thing for her birthday
>she wants to get some drinks and stuff in so she heads out to the shop for a bit
>a minute or so after she leaves, you hear your friend mumbling something quietly
>right as you go to ask what she said, you hear a hissing noise fill the room and suddenly your tummy starts to swell outward
>you look over in confusion, but just see your friend staring at you with a look of devious satisfaction
>"ahhh, they always look so adorable when they realise what that spell is doing"
>she gets up from the couch and saunters over to you, teasingly rubbing your inflating belly as if to savour her handiwork
>you feel the rest of your body fill with the same otherworldly pressure that currently occupies your belly, your butt and thighs pushing against the confines of your tight jeans as your lower half starts to blow up alongside your torso
>by the time you've gotten past the shock and confusion enough to actually try and do something, the swelling has already rendered your arms and legs too puffy and full to have anywhere near the required range of motion
>all you can do is sit there and let your captor tease you and taunt you as your clothes rip open and your torso slowly rounds out, your entire body nearing the point of being spherical
>"it's like I always say, you boys are just so much cuter an more tolerable as blimps"
>unbeknownst to you, her comparison is about to become even more apt
>finally, you feel your rear lifting off the sofa as you begin to float up towards the ceiling, uselessly flapping your limbs in some effort to gain control over your movement as you lightly rebound off the ceiling before settling in place
>you never considered how weird it would feel to have your belly touch the ceiling
>"now this is more like it, what's a birthday party without a balloon?"
>suddenly you're reminded of what you were even doing here in the first place, and that your girlfriend should be back eventually
>as if by fate, you hear footsteps outside followed by a key being placed into a lock
>this has been really fucking weird and you have no idea what your friend is doing, but at least your gf can help you now
>you watch the front door open, seeing your gf's jaw drop in wide eyed shock as she lays eyes on your inflated form
>she very nearly drops the shopping in surprise
>"Babe! What the fuck?"
>as bizarre as this has all been, you consider yourself thankful that, with any luck, the two of you are on the path to deflating you and getting everything back to norma-
>she runs to the other side of the room, not even looking at you before leaping into the waiting arms of your inflator
>you look on in confusion as the two of them sharing a warm, excited embrace
>"holy shit babe, I can't believe you actually inflated him"
>"I did say he'd make a better balloon than a boyfriend, didn't I?"
>"I mean, you do have a point."
>they giggle to each other
>"happy birthday sweetheart"
>the woman who just moments ago was using some manner of magic to inflate you like a balloon kisses your girlfriend on the cheek, prompting her to blush.
>"I left the best part for you, of course"
>your eyes widen in dawning realisation as your girlfriend steps over towards you, reaching up and pulling your balloon body down from the ceiling
>you can now see her facial expression up close, a deep blush washing over a look of nervous glee as she gently traces a finger over your exposed tummy.
"so big... So tight..." you hear her whisper to herself
>she looks into your eyes as she cups your puffy cheeks in her hands
>"...sorry" she says halfheartedly, giggling quietly to herself before pressing her lips to yours
>you've kissed many times before, but this is different
>a purely utilitarian action
>you hear her inhale through her nose before starting to blow into you, a hollow hissing filling the room as your inflation recommences
>you can hear her letting out quiet moans and whines of anticipation into the kiss as she pumps you up further and further
>it doesn't take you long to figure out why
>you realise your body is no longer getting bigger
>instead merely getting fuller
>harder to hold together
>right as you feel like you can't take any more, she finally breaks the kiss
>she holds you out at arms length from her, looking over your spherical form once more, before pulling you back in close
>at least she's stopped, you think to yourself, you're certain you couldn't take a single breath more or else you might p-
>"byebye, balloon boy~"