Apparently, having long blonde hair made it so that Karyn made the cheer team in 6th grade. Jon, not wanting his best friend to succumb to Sarah, joined also. Karyn and Sarah still hate each other, but are forced to get along because of cheer. While there was a guy's uniform at one point, the lack of male cheerleaders forced Jon to wear the girl's uniform. Needless to say, Jon was pretty upset about this development.
First, he says "I wish my next wish, and every after, will not change my gender." Then he says "I wish that the male cheer uniform still existed."