Green’s Dictionary of Slang

1. a disappointment.

1856		Dow Sermons II 316: I can’t help saying [...] that life is all moonshine – a monstrous humbug, – a grand suck in [F&H].
1881		Hawkesbury Chron. (Windsor, NSW) 24 Sept. 2/4: No fun at the Court House on Tuesday; all was decorum, and a dead suck-in for the expectant ones.
1903		J. Furphy Such is Life 6: Ever see sich a suck-in? Best at a distance, ain’t he?
1925		L. Doyle Dear Ducks 120: But they got a great suck-in, for there was nobody there but themselves.

2. (Aus./US) a cunning scheme; sharp practice; deceit.

1862		St Mary’s Beacon (Leonard Town, MD) 14 Aug. 1/6: Jonathon took a peep at the elephant [...] and returned with a woeful long visage. ‘What is it like?’ inquired jake. ‘A regular suck in,’ said Jonathon.
1865		Ballarat Star (Vic.) 25 July 4/1: The defendant gave an animated version of the story, saying ‘it was a dead suck in, my lord,’ as the bullock was not worth anything but the value of his hide.
1919		W.H. Downing Digger Dialects 48: suck-in — (1) Sharp practice; (2) a cunning scheme; (3) deceit.
1924		(con. WWI) A.G. Pretty Gloss. Sl. [...] in the A.I.F. 1921–1924 (rev. t/s) n.p.: suck-in. Sharp pratice [sic]; a cunning scheme; deceit.

3. (US Und.) a swindler.

1949

Monteleone Criminal Sl. (rev. edn).