Green’s Dictionary of Slang

perk n.²

(Aus.) beer.

1895		Coburg Leader (Vic.) 1 June 4/4: Those Epsom salts should be put in some ‘perk’ and given to the derktown’s donkey.
1913		Truth (Sydney) 6 July 3/1: A battalion of bobbies put in an appearance, and proceeded to search the house for perk. Their search revealed two demijohns [AND].
1914		Truth (Melbourne) 31 Jan. 8/8: The ‘something’ turned out to be a man [...] sleeping off the effects of too much perk.
1933		‘William Juniper’ True Drunkard’s Delight 228: If you particularly call for beer you may take your choice of reeb, purko [...] or gatter.
1969		Tennessean (Nashville, TN) 14 Dec. 5/3: Purko is beer.
1984		Partridge DSUE (8th edn) 936/1: purko Beer: military: ca.1870–1910.

In derivatives

perked (adj.) (also perk)

(Aus./N.Z.) drunk.

1906		E. Dyson Fact’ry ’Ands 95: Gettin’ perked in Odgson’s bes’ funeral suit, ’n’ cake-walkin’ on their King’s ’ighway with er flash tom on each fin.
1919		W.H. Downing Digger Dialects 38: perked — Drunk.
1925		(con. WWI) Fraser & Gibbons Soldier and Sailor Words 221: Perked: Drunk.
1972		J. O’Grady It’s Your Shout, Mate! 39: He was perk from his eyebrows to his bloody toenails.