Literally my first day of kindergarden before the school day even started, a fourth grader thought he would be the badass of the school or whatever if he bullied me on my first day, and I didn't have any of it; it quickly escalated and we started to fight.
Granted, I don't remember the fight itself much but what my parents told me of the aftermath, but I do know that I had no concept of how to fight, so I basically threw my arms and legs at him as fast and hard as I could before the teacher broke it up- he got a black eye and bloody nose, and I only got a black eye- victory, first-day kindergardener.
Again, I don't remember it much but the fact that there was a fight and I just threw myself around at him, my parents told me how bad a shape we were in, but I don't remember any blood, so I don't know...