Jen held the stone in her hand. "I wish that I would physically become a guy."
But nothing happened, because Jon had already accidentally and indirectly wished to become a girl. Wishes cannot be reversed. But Jen doesn't know this, since she thinks that everything else has changed instead of just her.
"Why didn't it work? What's wrong with this thing?"
"Maybe you should try again," Zoe said.
"Or maybe I should try saying it a different way."
"That sounds good."
"Okay. Here I go. I wish ..."