To blatantly ignore orders from a superior. Most often used by U.S. Marines (typically NCO's and SNCO's) to describe what younger Marines are doing when should be working. First used by a crusty old devil dog in the early 1900's by the name of Clifton Bledsoe Gates. Gates would later become the 19th Commandant of the Marine Corps.
Listen you shitbirds, get off your asses and quit gaffing me off!!!
But Staff Sergeant, I would never gaff off your orders?!?!