Green’s Dictionary of Slang

(Aus.) a damper.

1943		Baker Popular Dict. Aus. Sl. (2nd edn).
1996		E. Richards Outback Nights 86: ‘Damper was something you ate to stave off starvation between meals. It put a damper on your appetite.’ ‘So it means snack.’ ‘Out in the bush the swagmen and settlers called their damper other things. Dorkum or devil-on-the-coals’.