A short form of Assassin's Creed: Brotherhood, a historical fantasy third person action-adventure video game developed by Ubisoft Montreal. Also sounds like a crude sexual reference for the uninformed.
by NotScottKurtz November 24, 2010
Gay guy 1: So Brad and I are screwing every night now.
Gay guy 2: Are you guys dating?
Gay guy 1: No, he's afraid of commitment. We're just assbros.
Gay guy 2: Are you guys dating?
Gay guy 1: No, he's afraid of commitment. We're just assbros.
by Canopenerdude December 2, 2013