Green’s Dictionary of Slang

(Aus.) a condom.

1985		Pussy Rag (RMC Duntroon ‘underground’ mag.) in Moore (1993) n.p.: When was the last time that N had to get a fourthie to supply him with frangers so he could sly off to Sydney for a sly fuck?
1996		Penguin Bk of More Aus. Jokes 396: Being a member of a union is like using a franger – you get a false sense of security while being screwed.