Green’s Dictionary of Slang

(Aus.) a police informer, thus fizgigging, informing.

1878		Gippsland Times (Vic.) 27 May 3/2: These ‘fiz-gigs’ are professional criminals of the larcenous type [...] It is the ‘fizgig’ who meets the released prisoner as he emerges front Pentridge and ‘lays him on a good thing.’ [...] As soon as he has stimulated the evil propensities of the robber [...] he betakes himself to the little clique of detectives whose creature he is, and discloses the whole plot.
1882		Victorian Exp. (Geraldton, WA) 15 Nov. 3/6: Without their allies — ‘the fizgigs,’ the police seem powerless to trace the authors of the robberies which are now of such frequent occurrence.
1898		S. Aus. Register (Adelaide) 11 May 5/1: Among the words [...] which called forth enquiring interjections from Mr Justice Holroyd were a detective’s ‘phizgig’.
1900–10		Stephens & O’Brien Materials for a Dict. of Aus. Sl. [unpub. ms.].
1901		Bulletin (Sydney) 7 Dec. 37/1: They went away cursing all fizgigs, and informers, and blanky idiots of Police Sergeants.
1907		Lone Hand (Sydney) Sept. 523/1: The report [...] may indeed have tended to diminish ‘fiz-gigging’ by calling public opprobrium to the evil.
1915		Bulletin (Sydney) 11 Dec. 29/2: The utter currishness of the ordinary criminal is the detective’s salvation. Without the fiz-gig, the man who loses his nerve and gives the show away, the criminal courts might almost close up for all the work that would come their way.
1924		G.H. Lawson Dict. of Aus. Words And Terms 🌐 FIZGIG—Police informer.
1935		A.J. Pollock Und. Speaks.
1936		Newcastle Sun (NSW) 27 May 7/4: S.P. Glossary [...] Fizz gig, top off or pimp — A police informer.
1940		E. Curry Hysterical Hist. of Aus. 175: Actually, my dear pupils, he was a shelf, a fizgig, a top-off, or, to use more polite language, what is known as a police pimp.
1953		Baker Aus. Speaks v 124: A stool pigeon or informer, otherwise known as a fizgig, fizzer, shelf and topoff.
1967		‘Whisper All Aussie Dict.’ in Kings Cross Whisper (Sydney) xxxviii 10/2: phizzgig: A stickybeak, one who cannot mind his own business. Sometimes shortened to phizz.
1983		R. Aven-Bray Ridgey-Didge Oz Jack Lang 39: Phizzgig Police informer.
1996		(con. 1964-65) B. Thorpe Sex and Thugs and Rock ’n’ Roll 2: That June of ’63 King’s Cross was [...] brothels, hookers, pimps, hoons, charity molls, spruikers, toffs, chats, mooks, lairs, mugs, phizgigs, drag queens, straights, shines, bent cops, [...] tea leaves, neon, glitz.
1999		G. Seal Lingo 50: Equally Australian are a number of terms for the person who keeps guard for those involved in criminal activities, including cockatoo, nitkeeper (one who keeps nit), the crickety-sounding long-stopper and fizz-gig, or fizzer now used widely to mean a police informer.
2006		B. Matthews Intractable [ebook] [T]he historical evolution of the snitch and phizzgig to supergrass status.
2012		(con. 1943) G.S. Manson Coorparoo Blues [ebook] Either he was a fizgig, or he was there to tip off someone about Jack’s movements.