Not to be all serious and all, but why not just ignore the sad little fart, until someone with moderator priveleges notices, then remove the thread and ban the user.
A simple enough tactic which should result in the offender going away in boredom once he (I'm assuming male) realises no-one pays any attention to cares what he has to say.
Having said that, it IS a lot of fun tossing insults his way. :-D