Green’s Dictionary of Slang

a drinking party, a heavy drinking session.

1891		Pick-Me-Up 218/2: It is at least somewhat doubtful whether [...] remarks as to ‘fat-headed flipperty-flops having a booze-up’ can be included in the category of legitimate humour.
1897		Sessions Papers 26 Oct. 860: We [...] had a booze up together .
1903		‘Dads Wayback’ in Sun. Times (Sydney) 8 Feb. 4/1: [Life’s] nothin’ but graft, tucker, an’ sleep ; an’ ef some of us conldn’t ferget it now an’ again with a good booze up, we’d go fair dotty.
1914		Bulletin (Sydney) 6 Aug. 32/4: [B]ut he goes off with the swell, him not thinkin’, like you, Mister, that a pot does a man good after a booze up.
1929		(con. 1916) F. Manning Her Privates We (1986) 152: One Saturday night we was in there ’avin’ a bit of a booze-up.
1937		R. Westerby Wide Boys Never Work (1938) 93: Louie had a head on him after a booze-up the night before.
1941		K. Tennant Battlers 164: We’ll get Thirty-Bob and Dick out of quod and all have a big booze-up to celebrate.
1958		A. Sillitoe Sat. Night and Sun. Morning 169: [We] got two crates of beer out of the pub cellar next door. [...] We had a good booze-up from that.
1962		A. Wesker Chips with Everything II ix: The others have all gone to the Naafi [...] gone for a big booze-up.
1973		B.S. Johnson All Bull 34: What’s it to be? Strip-show or booze-up or what?
1989		A. Higgins ‘The Bird I Fancied’ in Helsingør Station and Other Departures 193: Aggressive Mohawks out for a night of booze-up and wog-bashing in dirty Leicester Square.
1999		Indep. Rev. 16 July 12: You go to a pub in the evenings and have a good old booze-up.
2000		Guardian G2 17 Mar. 13: An advertising industry booze-up.