Green’s Dictionary of Slang

food; thus hard munga, iron rations; soft munga, normal food.

1943		Sydney Morn. Herald 11 Dec. 7/1: The Arabic for food, mungaree [...] was quickly abbreviated to ‘munga’ and its use has been extended to ‘hard munga’, as distinct from ‘soft munga’. ‘Hard munga’ implies iron rations, or bully beef and biscuits, whereas ‘soft munga’ means normal rations, or meals enjoyed in civilian life.
1947		D. Davin For the Rest of Our Lives 344: We’d been topping our liquor off with a bit of manga, a bloody good feed of steak and three eggs each.
1959		(con. 1940s) G. Slatter Gun in My Hand 55: We sat in the stable resting up and waiting for the munga party to come up [...] The munga was slow coming up.
1963		(con. 1944) L. Glassop Rats in New Guinea 149: Sit down and have some munga, John.
1968		D. O’Grady A Bottle of Sandwiches 183: Munga, eh? Couple of steaks an’ a couple o’ bottles down by the beach?
1977		(con. 1941) R. Beilby Gunner 45: We weren’t too badly off for munga.
1983		R. Aven-Bray Ridgey-Didge Oz Jack Lang 14: The Beecham was again on his Pat Malone. He decided it was bird shit lime to put the nose bag on for some munga.