Green’s Dictionary of Slang

(Aus.) a cigarette.

1919		W.H. Downing Digger Dialects 30: jit — Cigarette.
1924		(con. WWI) A.G. Pretty Gloss. of Sl. [...] in the A.I.F. 1921–1924 (rev. t/s) n.p.: jit. A cigarette.