Green’s Dictionary of Slang

1. (Aus./N.Z.) second-rate, inferior.

1896		Kalgoorlie West. Argus (WA) 14 May 10/3: Within a month many of the stocks now slightingly referred to as ‘shy-poo’ scrip will be booming .
1902		Truth (Sydney) 3 Aug. 7/1: He was a solicitor of the ‘shypoo’ sort – that is, a lawyer who had few, if any, clients, and who lived ‘on his wits’ [AND].
1907		in M. Cannon That Damned Democrat (1981) 91: Now another attempt is to be made to still further gull the public, and get them into what is known, by mining men, at any rate, to be shypoo shows.
1915		Sun. Times (Perth) 10 Oct. 85/7: ‘If you think youi’re gettig it,’ said the shypoo sawbones, ‘keep away from the ship’s doctor’.
1927		Sun. Times (Perth) 14 Aug. 3/3: Shypoo [commercial] travellers, who insist upon payment without the goods being seen.
1941		Baker Popular Dict. Aus. Sl.
1952		C. Simpson Come away, Pearler 230: There’s half a dozen [...] decided the beer at the Dampo wasn’t such shypoo stuff after all [AND].
1955		N. Pulliam I Travelled a Lonely Land (1957) 239/1: shypoo – cheap or shoddy.

2. corrupt.

1903		Sun. Times (Perth) 26 July 1/1: [headline] Snide Auctioneers. Of sharks and sharkings in Sydney there seems no end, and one of latest snide affairs [...] is that of ‘shypoo’ auctioneers.
1904		Sun. Times (Perth) 28 Feb. 8/3: A lot of shypoo dealings go on in companies which never get to the directors’ ears.