troll

troll v.,n.  To utter a posting on {Usenet} designed to
   attract stupid responses or {flame}s.  May derive from the
   phrase "trolling for {newbie}s" or some similar construction.
   The well-constructed troll is a post that induces lots of newbies
   and flamers to make themselves look even more like idiots than they
   already do, while subtly conveying to the more savvy and
   experienced that it is in fact a deliberate troll.  If you don't
   fall for the joke, you get to be in on it.

   Some people claim that the troll is properly a narrower category
   than {flame bait}, that a troll is categorized by containing
   some assertion that is wrong but not overtly controversial.