Apparently not the brightest bulb in the shed, Luke does to his new footpaws exactly what he'd done to his chest, squeezing them both in an attempt to get rid of them. Unsurprisingly, the effect is the reverse: the air is pushed back up his body, stopping in his now pink and rounded stomach. However, something's different this time. To his surprise, there's a small, closed air nozzle where his belly button used to be. Apparently thinking that it might let the air out, he opens the nozzle.
You almost lose your string's grip on his wrist from the absolute hilarity of his reaction when the nozzle, rather than pouring air out of his stomach, starts quickly sucking air in. He starts fumbling frantically at it as his body starts puffing out beyond his gut, his waist and lower chest turning pink and inflating just slightly and the progression continuing, but he can't manage to get it shut again - the air flow is too strong for him to do it without concentrating, and he's way too frantic to concentrate. As the inflation reaches his chest and the tops of his legs, his pants and shirt barely able to hold in his big bunny parts, he finally realizes that he needs to take things a bit slower. Taking a deep breath, he grasps the nozzle with one hand, takes its cap with the other, and starts maneuvering it closed again. Unfortunately for him, he soon loses his grip on both the nozzle and the cap as his hands start to swell, taking on a familiar shiny shade of pink as his digits combine and his hands become rubbery mitts. He starts trying to force the nozzle shut again, but it's no use - he can't grasp it. All the while, the inflation finishes with his legs (his pants and shirt just barely managing to hold almost all of that bunny in them, with the exceptions of his tail, which peeks out over the back of his pants, and his gut, which shows like a beer belly past the bottom of his shirt) and starts moving up his neck. He starts screaming loudly, his voice rising several octaves the way it would if he was breathing in helium, and then his mouth expands into a rabbity muzzle with an audible pop. His cheeks expand like balloons (no surprise there), his eyes get taller as the top of his head grows just the slightest bit, and as the piece de resistance, his ears move up and extend until they're about a foot and a half long, flopping just slightly to complete the effect.
Luke, who now looks like a guy wearing a rubber easter bunny costume, is so freaked out that he runs out of the bathroom, to which he's instantly met with a massive amount of stares, snickers, and chuckles. Putting his mitts over his face like he expects it to hide everything, he runs off, and your total delight at it all is so great that you actually do lose your grip on his wrist, your string hanging limply as he makes his escape. You can't remember ever having fun like that as a human, and can't wait for your next vict- er, owner.
Luckily, you don't have to wait long. A tall, brown-haired 19 year old who had been laughing particularly hard at Luke grabs your string, chuckling to himself. "Ha, looks like that poor bunny wunny wost his widdle balloon! Well, I guess I'll just have to hold on to it until he gets back!" You can tell by the tone of his voice that he actually intends to take you so that he can go and hide you somewhere that Luke'll never get you back, but you're fine with that. After all, the way he talks is so unbelievably cheesy that he's just asking for a little bit of "fun" with you.