Joe Jerk Off

A variation of "Joe Schmoe", this term is used for someone who inserts their opinion when not asked. Additionally, this person thinks they know what they're talking about, even though they have no experience or knowledge on most subject being discussed. You might say a Joe Jerk Off is a member of the Peanut Gallery.

Guy #1: Do you hear this guy talking about shit he knows nothing about?
Guy #2: Yeah, he's a real Joe Jerk Off