Green’s Dictionary of Slang

1. boots, shoes; thus move one’s crabs, to run off.

1791		‘Flash Lang.’ in Confessions of Thomas Mount 18: Shoes, crabs.
1807		H. Tufts Autobiog. (1930) 292: Crab signifies a shoe.
1821		D. Haggart Autobiog. 133: Few had either a mill tuig, toper or crabs.
1839		H. Brandon Dict. of the Flash or Cant Lang. 162/1: Crabs – shoes.
1846		Swell’s Night Guide 61: Twig his gams; stage his mud fakers – there’s a pair of crab spoilers. [Ibid.] 74 : No gentleman can dance in queer crabs, or hob-nail’d trampers.
1848		Bell’s Life in Sydney 26 Feb. 1/4: So I gets [...] these ere crabs, watch, and togs, so I’m a Svell un vith a caser in this ere cly.
1857		‘Ducange Anglicus’ Vulgar Tongue.
1861		Bell’s Life in Sydney 22 June 3/2: Ladies boots, by some unaccountable means, became animated [...] the ‘crabs’ invariably promenaded at dinner hour.
1889		Clarkson & Richardson Police! 346: This class of thieves [...] always go about the house with their ‘crabs’ off.
1895		Truth (Sydney) 12 May 5/3: I bought a shirt and a pair of crabs.
1898		Binstead & Wells A Pink ’Un and a Pelican 245: Their eyes follow every movement of the burly ‘chucker’ as he rolls round the hogshead of precious ‘crabs’.
1905		Sun. Times (Perth) 5 Feb. 4/7: ‘Fifteen bob [...] and I’ll be rammed, jammed and double banged into the fifteenth part of a rotten ham if I take a penny less or a farthing more’ [...] ‘Here’s 12/6 and the crabs are mine’.
1910		Bulletin (Sydney) 25 Aug. 15/1: To get a pair of ‘crabs’ half-soled and heeled costs Port Moresby only three bob.
1923		Smith’s Wkly (Sydney) 11 Aug. 15/2: The pup poisoned, hang crabs round bushel and neck [sic] [...] Glossary Bushel and Peck: neck.
1935		A.J. Pollock Und. Speaks.
1937		Thieves Slang ms list from District Police Training Centre, Ryton-on-Dunsmore, Warwicks n.p.: Crabs: Boots and shoes.

2. the feet.

1859

Matsell Vocabulum.