Again, ignoring Biff's question, Karyn focused on the best way to fix what Jon did to Nadine and her friends, or at least "help" them out. While she didn't personally know the families of Nadine and her friends, she knew their kind. If their parents ever found out that they were gay ... well, they wouldn't handle it very well.
So, that's why Karyn said "I wish that if any of the parents of Nadine, Tina, or Paul discover that any of their children is gay that the parents will both accept and support the fact that they're gay." The stone glowed, granting the wish. "There, that should do it. Now for Jon."
"No!" Jon (Boopsie) yelled.