"I wish I knew how to make Karyn a girl again."
And just like that, Jon knew the wish he had to make. Biff's last wish wasn't too specific, after all. He had wished "we" would change into guys, not Karyn, so it could be reinterpreted. "I wish that the 'we' affected by the previous wish meant only Biff and his friends, not Karyn or me."
So Karyn turned back into a girl, with her original hair and breasts.
"I wish that Biff and his friends who were transformed into cheerleaders like being cheerleaders and don't want to change back. I also wish they are at home, they can never hurt me or Karyn, that nobody blames me for Sarah being sick, and that only me and Karyn remember about the wishing stone."
Which was the end--almost. Jon and Karyn were busty cheerleaders, and that really was too specific.
Jon's mom leaned out of a back window of the house. "Jonnie!" she yelled. "Isn't your cheerleading practice supposed to be soon? You'd better get going...."
