B(ad) A(ss) M(other) F(ucker). This is a term used for extremely sexy or generally fuckin awesome people. Use this term sparingly, because not many people deserve to be called a B.A.M.F.
Nikolai Fraiture of the Strokes is such a B.A.M.F. He is not only sexy, hot and hilarious, but he is the bad ass bass player. Your mom wishes he would fuck her.