Green’s Dictionary of Slang

Anzac adj.

[the term Anzac appears in 1915 (in C.E.W. Bean’s diary) as an acronym formed from the initial letters of Australian and New Zealand Army Corps, orig. used as a telegraphic code name for the Corps. In the same year it was used as an abbr. for ‘Anzac Cove’ at Gallipoli, and then as a term for the ‘Gallipoli campaign’. In 1916 it was first used to refer to a member of the Australian and New Zealand Army Corps who served in the Gallipoli campaign. In honour of the fact that they fought at Gallipoli, the Anzacs were commanded in 1919 to attach a small brass ‘A’ above the colour patch on their sleeve. During the war the term ‘Anzac’ was used in various compounds: an Anzac button was ‘a nail used in place of a trouser button’, Anzac soup was ‘shell-hole water polluted by a corpse’, Anzac stew was ‘an urn of hot water and one bacon rind’, and an Anzac wafer was ‘a hard biscuit supplied to the AIF in place of bread’. These terms did not survive their wartime contexts, although the Anzac wafer survives transformed into the Anzac biscuit (and, more recently, the Anzac cookie)]

In compounds

Anzac day dinner (n.) [Anzac Day, a public holiday held on 25 April (the anniversary of the Gallipoli landing in 1915) in Australia and New Zealand in memory of the nations’ war dead]

(N.Z.) a meal, usu. lunch, that is mainly (if not entirely) composed of alcohol.

[UK]R. Hyde Nor the Years Condemn 162: He crawled into bed [...] Too much Anzac day dinner and Macnamara made him look silly in the pub.
[NZ] McGill Reed Dict. of N.Z. Sl.
Anzac poker (n.)

(Aus.) a form of criminal gambling game using cards.

[Aus]Tweed Dly (Murwillumbah, NSW) 16 July 5/1: Five Australians [...] were to-day sentenced to five years’ gaol each at the Old Bailey on the charge of having obtained money by betting card tricks and Anzac poker.
[Aus]Uralla Times (NSW) 17 May 4/5: In one particular instance, the gang rooked a well-known sportsman from London of £5000 at a game called Anzac poker.
[Aus]Cessnock Eagle (NSW) 2 Aug. 7/3: He was extradited from Monte Carlo, where he had been engaged with Biggar and Warren in trying to get £5000 from another well known man by the game of ‘Anzac Poker’ as the gang called it.
[Aus]Truth (Sydney) 1 Feb. 4/3: Biggar and his gang specialised in cheating victims - chiefly wealthy Americans or colonials - at auction bridge or ‘Anzac poker’.
Anzac shandy (n.)

(N.Z.) champagne; a mix of beer and champagne drunk by WW1 troops.

[US](ref. to WW1) P. Howard State of the Lang. 36: Anzac shandy (a mixture of beer and champagne favoured, or at any rate desired, by Australian and New Zealand troops in the First World War).
[NZ]McGill Reed Dict. of N.Z. Sl. 11: Anzac shandy Champagne.