Green’s Dictionary of Slang

(Aus./N.Z.) tipsy, semi-drunk.

1955		N. Pulliam I Travelled a Lonely Land (1957) 233/2: half rinsed – ‘half there’.
1984		Partridge DSUE (8th edn) 522: since ca. 1912; perhaps a little later in Aus.
2003		McGill Reed Dict. of N.Z. Sl.
2001		(con. 1945–6) P. Doyle Devil’s Jump (2008) 12: There was a bottle of rum on top of Max’s piano and he was already half-rinsed.