Green’s Dictionary of Slang

(Aus.) to drink beer; thus ext. to celebrate, to have a good time.

1869		Border Watch (Mt Gambier, SA) 17 Nov. 2/3: ‘The fact speaks for itself.’ Speaks what? After blowing the froth off, we have looked searchingly into the matter, and cannot for the life of us guess what it speaks.
1905		Sydney Sportsman (Surrey Hills, NSW) 9 Aug. 5/4: [H]e had a habit, after blowing the froth off a dozen or more tankards of ’arf-and-’arf, of talking mysteriously of future greatness.
c.1910		L. Esson ‘Jugger’s Out Ter-d’y’ in Seal (1999) 39: Won’t we blow the froth orf!
1914		Bulletin (Sydney) 26 Nov. 44/1: The first pub I sights I drops into... blows the froth off, squints at the hempty glass, an’ says to the cove be’ind the bar: ‘Can yous gimme me change fer a note?’.