Since Jon knew that the stone was twisting wishes, you'd think that he would have been a bit more careful with his wishes, but no, he wasn't.
Karyn looked at him in shock. Or rather, she looked at her in shock. Instead of Jon's uniform changing to match his gender, his gender changed to match his uniform. Jon had become a girl!
"What have I done?" Jon said, in his higher-pitched girl's voice.
