The M.A.N., or Masculine Acknowledgement Nod, is a gesture performed predominately between males and involves a quick, upward nod intended to show recognition of a fellow dude. While the M.A.N. is most often exchanged between friends or acquaintances, it can also be used on random passersby.
While at the local hardware store, Jim noticed the maintenance guy from his apartment building checking out the pipe wrenches and instinctively gave him the M.A.N., which was quickly reciprocated.
by BallPeen May 13, 2013