Green’s Dictionary of Slang

1. (Aus./N.Z. ) a lavatory.

1941		Baker Popular Dict. Aus. Sl. 66: Shouse, a privy.
1951		D. Stivens Jimmy Brockett 214: I seen that now as plain as a country shouse.
1957		‘Nino Culotta’ They’re a Weird Mob (1958) 43: ‘Take ’em orf matey.’ [...] ‘Yeah, chuck ’em ter the shouse.’.
1968		J. O’Grady Gone Troppo (1969) 157: Hobbling up and down to the shouse with a guts-ache and a crook ankle.
1976		D. Ireland Glass Canoe (1982) 125: There’s a stiff in the old shouse.
1982		N. Keesing Lily on the Dustbin 48: The word ‘toilet’ used to be considered a dreadful genteelism by Australians with pretensions to plain usage, they preferred lavatory, which is itself a euphemism. ‘Toilet’ won and became universal, though it is considered very ‘in’ in some circles to revert to words like ‘dunny’ and ‘sh’ouse’ (from ‘shit-house’), or to adopt such overseas term as ‘loo’ or ‘john’.
1993		B. Moore Lex. of Cadet Lang. 330: Gillie’s shouse i.e., Gillie’s Shit-house (of which shouse is a syncopation).
2003		McGill Reed Dict. of N.Z. Sl.

2. attrib. use of sense 1.

1968

(con. 1940s) G. Slatter Pagan Game (1969) 71: He had heard a shoush rumour that they were going down to Trasimeno.

3. something exceptionally bad.

1988

McGill Dict. of Kiwi Sl. 102/1: shouse something very bad; contraction of ‘shithouse’.