Named so because of the line in the song "Incredibad" from The Lonely Island's album of the same title, "One in the front and two in the back."
Guy #2: Yeah, ever since I heard that song... Shall we ask Steve to do it with us?
Guy #1: If you must. We need to find a girl first though otherwise it's gonna turn out Incredigay!
Guy #2: No. Just no. *shakes head*