Green’s Dictionary of Slang

1. (Aus./N.Z.) drunk.

1898		Kilmore Free Press (Vic.) 28 July 2/4: A drunk [...] said he had only two drinks that day, but that he was stunned.
1906		Salt Lake City (UT) 30 Mar. 4/5: He is [...] tangled, stunned.
1919		W.H. Downing Digger Dialects 48: stunned (adj.) — Drunk.
1924		(con. WWI) A.G. Pretty Gloss. Sl. [...] in the A.I.F. 1921–1924 (rev. t/s) n.p.: stunned. Drunk.
1933		A.E. Strong in Partridge Sl. Today and Yesterday 288: He deserves his liberty to-night, and even if he gets stunned he deserves it.
1943		J.A.W. Bennett ‘Eng. as it is Spoken in N.Z.’ in AS XVIII:2 Apr. 89: A thoroughly drunk man is stonkered, floored, stunned.
1969		J. Hibberd Dimboola (2000) 98: Just look at him! Just look at him. Looks like a stunned mullet [...] It’s an alcoholic stupor!
1988		McGill Dict. of Kiwi Sl. 109/2: stunned drunk.
2003		McGill Reed Dict. of N.Z. Sl. [as cit. 1988].

2. (US gay) intoxicated by a drug.

1972

B. Rodgers Queens’ Vernacular 191: stunned (camp) stoned.