a person who shows that they "know it all" when in the audience might assume otherwise, they are considered know-it-alls, but now there is a new word for it! Factard, not two Ts just one. ; )
Billy_Knowitall: Actually, you are wron...
Joe_Dumberer ...Gah Billy you're such a factard!
"You think you know everything but you don't, you're such a factard!"