When you use the term bullies, it seems as if you're in middle school? How old are you? If you're not really in your teens, then you could find some other way to scare them off besides beating them down. Violence isn't always the answer.
If they truly are bullies, and not brave ones, you just need to show them that you're not going to be pushed around.
Another idea would be to carry an improvised weapon. Something inconspicuous, like a hard object in your pocket. That way it wouldn't be called a weapon, and say you just felt so scared that you felt you had to defend yourself.
Good luck, and I personally don't want you to kill someone.
