If you're abusive; swearing, harrassing, bullying other users... If 你 use offensive content; offensive 评论 (I guess) 或者 if 你 spam; 你 give someone an unnecessary number of props.
I'm not really sure, bot those are my best guesses :)
If you're worried, I'll warn 你 about these three known abuses that can be done on Fanpop.