Bill-doh 

<Noun, V.tra.; V.intra.> Netspeak. A contraction of bulletin boards ([B.B.)and the expression "DOH!" as spoken by Homer Simpson from the T.V. series "The Simpsons". AKA: B-DOH! or BB-DOH!]
(1) Someone who joins an internet message board (Bulletin Board; B.B.) with their true name with the sole intention of defaming another person, ultimately making the target of the attacks look more credible. (2)To act like an authority while being an amateur in attempt to disredit another on a B.B.
(3) To act without thinking; to speak first and think later in an attempt to discredit someone online. (4) To flop, fail or defraud others without validated claims.

"That poster is a Bill-doh."
"Don't listen to that Bill-doh"
"Did he just 'Bill-doh' the message board?"
"I think you totally Bill-doh'd your posts."
"You silly Bill-doh is too much, fool."

Bill-doh by Apemonkey August 4, 2008