The rock began to make odd noises as the wishes started to fade off one by one. Karyn's breasts shrank, her hair turned from red to black to blonde. Jon changed from his form, to the female form Sarah had wished him into, to the form Karyn wished him into, to Sarah's form, back to his original form, sort of in a cycle. Sarah's body parts would turn back into her own, then turn back into Jon's. It wasn't long before the stress of it all had the three convulcing on the floor. Then, there was the explosion....
The explosion didn't ruin any structures, just change people. Jon, Sarah, & Karyn were the first to notice.
Jon found himself in Karyn's recent goth form, no piercings, but at least his breasts were down to Karyn's original size.
Karyn found herself in an idealized version of Sarah's body. Same age and basic look, just a little more...perfect. Kind of like a supermodel, as opposed to just the popular kid.
Sarah still had Jon's body, except with those darn large breasts that were formerly on Karyn, and she still had her old face, which looked a little more than out of place.
Jon looked at the rock, it had turned black. "I wish the walls were green." He said. Nothing happened. "Damn! We must've broken it."
Then they heard a scream from downstairs! How far had the effects of that explosion gone?