Jon jogged out of the theater and down the hall to the restroom. He never felt like urinating this much in his life. Soon, his jog turned into a run, and then he finally got to the restroom. (Why were they always so far away?)
He darted towards one of the urinals, unzipped his pants, and let himself go. But it didn't go exactly as planned. Urine began to drip down his pants and his legs. And when he looked down, he understood why. He had no penis. Instead, he had a vagina.
"Karyn!" he shouted, knowing this was her fault. She hadn't just made his nose bigger. She had done other things too. In this case, she had removed all of his body hair from his neck down and replaced his male sexual organs with female ones. So now, he was technically a girl, even though his body still had a masculine frame and no breasts, and also his own male voice, face and hair. In fact, if no one saw what was between his legs, they'd think he really was a boy.
Karyn did make that wish for Jon to know how his body used to be before she made her last wish, but this wish had a catch. Jon could only notice what was different after Karyn said the phrase "full bladder", which would also, in turn, cause Jon to have an overwhelming urge to urinate, thus completing the "prank".