Green’s Dictionary of Slang

(orig. US) tipsy, mildly drunk.

1838		J.C. Neal Charcoal Sketches (1865) 13: If your tongue wasn’t so thick, I’d say you must mosey: but moseying is only to be done when a gemman’s half shot.
1896		W.C. Gore Student Sl. in Cohen (1997) 18: shot a. Intoxicated. ‘He was about half shot.’.
1906		Salt Lake City (UT) 30 Mar. 4/5: He is [...] half-shot, half-gone .
a.1918		G. Stuart Forty Years on the Frontier I 174: Charlie, ‘half-shot’ came along and begun to issue orders [DA].
1926		Wood & Goddard Dict. Amer. Sl. 48: shot. Drunk. Hence, half-shot. Half-drunk.
1931		A. Hardin ‘Volstead English’ in AS VII:2 88: Terms referring to the state of intoxication: [...] Verbs: Shot, half shot.
1949		J.R. Cole It was so Late 10: ‘Don’t shoot the barman, he’s half shot already.’ [...] ‘Bit of a session, eh?’ [OED].
1952		G. Meek ‘The Ballad of the Rouseabout’ Station Days in Maoriland 95: Gun shearers who, big tallies do, / When half-shot at the pub.
1954		Mad mag. Dec. 22: Me not Pot-Shot Pete! My name Half-Shot Shemete!
1968		D. Ireland Chantic Bird 29: They’d bottle you for two bob if they thought you were half shot.
1979		H. Leonard A Life (1981) Act II: You could drink Jameson’s distillery dry, and you might get half shot.
1981		J. Henderson Exiles of Asbestos Cottage 14: Plenty of garrulous half-shot but willing hands had all the wool stacked safely in the store.
1995		I. Rankin Let It Bleed 109: Aye, and maybe he’s half-shot and sleeping it off.
2001		(con. 1945–6) P. Doyle Devil’s Jump (2008) 51: They were both more than half-shot when we finally left the Rocket Club.