Green’s Dictionary of Slang

(N.Z.) food, a meal, esp. lunch.

1988		McGill Dict. of Kiwi Sl. 74/1: mungas/munja Kiwi version of ‘mungey’ , Services slang for ‘food’; possibly from French ‘manger’, to eat, possibly borrowed in Crimean War.
2003		McGill Reed Dict. of N.Z. Sl. 138: munga/munger/munja Food or a rest break to have a smoke. Army slang ANZ.
2023		R. Milward Man-Eating Typewriter 127: [M]any seem more interested in the complimentary bovaries and munja.