Where did those come from?

Before Karyn could wish for their shirts to swap, she noticed something was different. Very different. "Jon, I didn't make any wishes. Why do you have boobs?" she asked. Jon looked down at himself, and his jaw dropped when noticed that he could read his new shirt much easier, since the lettering was being held up by the most perfect pair of C cup breasts he'd ever seen. "Uh..." was all he could respond.