I've never lost a fistfight because I've always won by the maneuver of courageously running away in a manly fashion, or getting the assailant to fight someone else instead.
When I was in like 6th grade I think a Korean kid started fighting me in the dorms of our school because he wanted to play Starcraft and I didn't feel like leaving because I wanted to talk to his roommate. I was so stunned when he threw the first punch that he managed to get a few more in before he backed off. I cried a little bit afterwards.
It's not a very exciting story but it's the only fistfight I've lost (and I've only been in 2 so a 1:1 k/d isn't that bad r-right)
This kid who was like my worst enemy in 5th grade was teasing me. Don't recall what he said but it set me off. I was holding the handle for my violin case and I just swung and hit him in the nose with the top part of the case. He dropped crying and I just thought "I'm going to juvie!" His fat ass friend pushed me and was like "wtf you doing?" I was confused because I didn't know they were friends and he charged me into the corner of a brick wall. I can still feel a scar in the back of my head.
I also lost a fist fight to a Puerto Rican, not my finest hour.
When I was 16, I started a fight with some guy who was kicking a football at my friends. I hit first and broke his nose, he went down to the floor and I reveled in my victory. Then I got hit from the side and was on the ground with 6 guys beating the shit out of me.