Depends. When I was in 2nd grade, this kid used to make fun of me and push me over and the teachers wouldn't do anything about it, so I started a hate club against him and got him in trouble for things we did, and eventually he got kicked out of school. I probably wouldn't be that vengeful now. But if I really wanted revenge for something horrible committed against me, I'd wait for an opportunity to do it anonymously or in a way I could get away with it.