Okay, so, I think a lot of people have seen some of the things "FuckYouAll" is posting.
(I dislike making a quote about them because I know they're just going to get a kick out of the attention, but things need to be said).
Firstly, I know they're saying a lot of things that are crude and cruel, but you have to remember that they're a person, too. You don't like people calling you "ugly" or "stupid", I know you don't. Nobody does. Remember that. Even though this person doesn't care, or acts like they don't, it doesn't matter. Don't stoop to their level and call them names back.
Secondly, this person only comes on this site to get everyone riled up and angry. Commenting on their profile, making quotes about it, etc., only gives them the attention they crave. (Hypocritical, I suppose. But whatever. That's the truth. I know this quote is going to get plenty of feedback).
Basically, ignore them and they'll go away. If no one pays any attention to them, they won't have a reason to post anymore.