Oh man, I screwed up bad.
The first thing off the top of my head is, I shouldn't have spat my chewing gum in that girl's face.
Secondly, I shouldn't have been a coward when this cute girl found out I liked her.
I wouldn't have tried spending so much time with the "cool kids" in grade school. Hell, that was a waste, I didn't even have much of a sense of self at that point.
... Damn, I screwed up bad...
I remember one time, I was at camp, and a girl liked me, and wanted to go to the banquet with me, she told a friend of mine, who asked me if I liked her. I said "no" because I knew that my best friend wanted to go with her. This happened at breakfast, and when I went outside, the next thing I know, this girl who I thought was extremely cute went bat-@#$% insane and cussed me the hell out in front of everyone.
If I went back in time, I probably wouldn't have changed a thing.