Troll-O-Meter n. Common Usenet jargon for a notional instrument used to
   measure the provocation level of a Usenet {troll}. "Come on, everyone!
   If the above doesn't set off the Troll-O-Meter, we're going to have to
   get him to run around with a big blinking sign saying `I am a troll, I'm
   only in it for the controversy and flames' and shooting random gobs of
   Jell-O(tm) at us before the point is proven." Mentions of the
   Troll-O-Meter are often accompanied by an ASCII picture of an arrow
   pointing at a numeric scale. Compare {bogometer}, {Indent-o-Meter}.


Source: The Jargon File