Jon didn't hear the wish, so he thought that he (she?) had always been Karyn. And as Karyn, she was still mad at Jon for being so rude. She grasped the rock in her hand...
As far as she knew, she had just wished that Jon had her breasts. Of course, the real Karyn had wished that. But Jon/Karyn thought he was Karyn, so she remembered making the wish too.
Jon/Karyn wondered: she obviously still had the breasts. In fact, the wish didn't seem to do anything. Maybe it was because as Jon had said, the wishes aren't reversible?
She'd have to wait until morning to see what had happened to Jon, if anything. Probably nothing--she had just tried to reverse a wish.
By the next morning, Karyn (in Jon's body) was much less angry. After all, she realized, Jon had voluntarily given the stone to her. That was actually a pretty big thing. She'd have to go talk to Jon, tell him she didn't mean it, and figure out a way to swap back.
By the next morning, Jon/Karyn was much less angry. After all, she realized, Jon had voluntarily given the stone to her. That was actually a pretty big thing. She'd have to see if the wish affected Jon....
Karyn met Jon on the way to school.
"Look, Jon, I'm sorry," said Karyn in Jon's body.
"What?" replied Jon/Karyn. "I'm not Jon. You're Jon... aren't you?"
"No, I'm Karyn. I wished Jon would have my breasts and we swapped bodies..."
"I'm the one who wished that, and nothing happened!"
"Wait a minute," said Karyn in Jon's body. "We both seem to be me. I'm Karyn and so are you..."
"But I have the rock," said Jon/Karyn. "You wished it to come to me."
"No," said Karyn in Jon's body. "Jon wished the rock to come to me. Then we swapped. So now Jon in my body has the rock..."
"Let me get this straight," said Jon/Karyn. "You are Karyn and remember being Karyn. I'm actually Jon, but I remember being Karyn too. We both think we're the same person?"
"That's right, I think," said Karyn in Jon's body. "We need to change you to remember Jon's life."
"But I remember my whole life already. I remember being a girl, being friends with Jon, making the wish about my hair and breasts... you can't just get rid of that."
"You mean you don't want to be changed to remember being Jon again?"
"No... I mean, Jon's my friend. Our friend. But I'm not Jon. At least I don't think of myself as Jon..."
"But I'm certainly not Jon," said Karyn in Jon's body. "We have to do something. Can you think of a wish?"
"Sure," said Jon/Karyn, taking out the stone before Karyn could stop her. "I wish...."