Watching in astonishment, the wyvern observed as the gecko's limbs began to swell, his cheeks puffing up, his clothes beginning to pop apart at the seams, and his body growing louder and louder while the sound of air hissing filled the room, not unlike a balloon being filled up with a tank of helium. "N-Narid- BHUUUORP! -w-what's happening to m- BUUUURRRP!" Watermelon cried, unable to get many words out before the carbonation would rise up his throat and escape as a loud belch.
Even the massive releases of air weren't enough to mitigate his incredible growth, as it seemed with each burp he'd only somehow agitated the soda within his belly even further, accelerating his inflation. Before long, his arms and legs were beginning to merge with his nearly spherical torso, his tail inflating like a balloon animal and his chest beginning to push into his chin, making burping out any more air difficult, as well as making simple speech even more complicated.
Narid, stunned silent, could only watch.
Finally, the gecko's growth came to a gradual halt just as his hide began to ominously creak and groan, leaving him a nearly perfect sphere with divots where his hands, head, and feet barely stuck out from his orbular body, his clothes reduced to tatters that now barely clung to him.
Narid stared up at the gecko, who stared back with widened, panicked eyes. The wyvern sheepishly smiled and could only muster, "Ehm... I think I put a bit too much carbonation in that."