Doesn't matter; the poor child climbs the fence for no other reason than to protest, and I think that's childish as the teacher. (Who, by the way, says: "Don't climb that fence!! Don't ask why! It's because I said so! I'll take you to the principle's office if you do, and make sure you don't come to school for a week!")
I just realized something: one person is a bully (who are real threats), and the other person is just provoking that bully. (Maybe that's a better schoolyard analogy.) In essence, both are bullies.
EDIT: Addendum: the original bully is a sports-player, and the retaliating bully is bullying all other sports players.