Army slang for the Browning M2-HB .50-caliber heavy machine gun
"Go grab me a couple of boxes of fifty-cal. I'm gonna make the Ma Deuce sing!"
by Bullzeye December 26, 2003
"Mas" is Spanish for much, "Deuces" is latin for 2 but in the modern age has been used to symbolize the two finger peace sign hence, "deuces" for the two fingers. Usually used together as a farewell statement to close friends. Literally means, "much peace".
Speaker 1: "It been fun, see you tomorrow!"

Speaker 2: "Okay, mas deuces!"( Holds up peace sign after farewell handshake)

Speaker1: "Mas Deuces, homie." (Holds up peace sign after farewell handshake.)
by Matt Spoon October 8, 2010
Ma Deuce is on the Loose is military slang, for the effective use of a M-2 .50 heavy machine gun in combat.
The sappers try to cut the perimeter wire, but they get cut down when Ma Deuce is on the Loose!
by I, Wreckerrr October 13, 2016