cloak, n. — Green’s Dictionary of Slang

cloak n.

1. (UK Und.) a watch-case.

1718		C. Hitchin Conduct of Receivers and Thief-Takers 15: A Suit, alias Gold-Watch, or two or three Cloaks, alias Gold-Watch Cases.
1839		(con. 1715) W.H. Ainsworth Jack Sheppard (1917) 141: A fence, or receiver, bargaining with a clouter, or pickpocket, for [...] two cloaks, commonly called watch-cases.
1890–1904		Farmer & Henley Sl. and Its Analogues.

2. (Aus. Und) . one who spreads open their cloak to hide a confederate involved in pickpocketing or shoplifting .

1848

Bell’s Life in Sydney 8 Jan. 2/6: The tailor performed the dignified office of cloak, expanding the wings of his seedy surtout so as to hide the manipulatory depredations of his pal.

SE in slang uses

In compounds

cloak-and-suiter (n.)

(US) a wealthy individual.

[1919		F. Hurst ‘Boob Spelled Backward’ in Humoresque 226: How is it all of a sudden a girl in the wholesale ribbon business should have the trade to entertain like she was in the cloak-and suit chorus?].
1924		E. Ferber ‘Classified’ in One Basket (1947) 228: Whitey’s got it so all over these fat cloak-and-suiters I see you running around with.
1938		A.J. Liebling Back Where I Came From (1990) 109: In the lush days of the cauliflower boom, the game was invaded by cloak-and-suiters [...] seeking to invest their surplus profits in prizefighters.
1947		C.S. Montanye ‘Frozen Stiff’ in Popular Detective Mar. 🌐 Hagen picked him up for working a squeeze play on a cloak-and-suiter from out of town.

cloak-twitcher (n.)

(UK Und.) a thief specializing in the theft of cloaks.

1725		New Canting Dict. n.p.: cloak-twitchers Villains who formerly, when Cloaks were much worn, us’d to lurk, in by and dark Places [sic], to snatch them off of the Wearer’s Shoulders; as now their Descendants of the Tribe, do by Peruques, Hats, &c. The Thirty-third Order of Villains.
1734		C. Johnson Hist. of Highwaymen &c. 142: They take Cloaks likewise, and glory in having got such a Purchase at the Point of their Swords; for which Gallantry they are called Silk-Snatchers; whereas we (who lurk in Corners, and prey upon all Passengers without Distinction) have the general Appellation of Cloak-Twitchers.
1737, 1759, 1760, 1776		Bailey Universal Etym. Eng. Dict.
1785, 1788, 1796		Grose Classical Dict. of the Vulgar Tongue n.p.: Cloak twitchers, rogues who lurk about the entrances into dark allies, and by lanes, to snatch cloaks from the shoulders of passengers.
1811		Lex. Balatronicum.
1823		Egan Grose’s Classical Dict. of the Vulgar Tongue.