Green’s Dictionary of Slang

1. a coat or a waistcoat.

1781		G. Parker View of Society II 174: A highwayman will ding his Upper-Benjamin, his Jazey, his Sticks, his Flogger, his Diggers, his Beater-Cases, &c. and having all these on him when he committed the robbery, is totally transformed by dinging.
1824		Emerald (N.Y.) 16 Oct. 109/1–2: A retreat was the consequence — up with the stakes; on with the Benjamins — old the reins — jee-up — lash away — God help bad horsemen, and mercy to decayed rattlers: — broken noses and crushed springs. Jee-up, and we were soon at the Sand course, near Jamaica.
1824		Annals of Sporting 1 May 361/2: Swells in their drab benjamins and best felt beavers.
1825		Sydney Gaz. 3 mar. 3/4: I will freely stake my old black benjamin against your satin breeches.
1830		Egan Finish to the Adventures of Tom and Jerry (1889) 309: To Philip Timothy Splinter, Esq., I bequeath my upper tog, my Benjaman, my wrapper, generally called a top coat.
1833		M. Scott Tom Cringle’s Log (1862) 35: Benjamins, and great-coats, and cloaks of all sorts and sizes.
1840		H. Cockton Valentine Vox 549: As soon as I’ve got off my benjamin.
1845		‘A Week in Oxford’ in Bell’s Life in Sydney 25 Oct. 4/3: [...] whose ‘varmint pink’ may be seen peeping out beneath the cuffs of their ‘big bens’* *Anglice, great coats.
1847		Bell’s Life in Sydney 30 Oct. 2/4: [...] protruding his chin from beneath the velvet folds of his Benjamin.
1851		G. Borrow Lavengro II 276: The coachman was replaced by another [...] with narrow-rimmed hat and fashionable benjamin.
1855		Broadway Belle (N.Y.) 29 Oct. 1/3–4: Nixey tipping the slums but sherry down the kid with my other benjamin and a slum or two, for the peck is awful quisby.
1868		J.D. McCabe Secrets of the Great City 359: The Detectives’ Manual gives a glossary of this language, from which we take the following specimens [...] Benjamin.—A coat.
1876		St Louis Globe-Democrat 19 Jan. n.p.: Whereupon, the party addressed takes an inventory of his friend’s clothes and in reference to his overcoat exclaims, ‘Oh what a Benjamin’.
1877		‘Larry Cafooslem’ in Laughing Songster 159: My coat was a bit of blue, / And a ‘Benjamin’ smart beside.
1885		Bulletin (Sydney) 18 July 12/1: And, formerly, when a Bathurst man wanted his drop o’ good beer to wash down his Sunday dinner, he used to walk openly through the streets with the family wash-jug. Now he plants a quart bottle in the tail of his ‘benjamin,’ and, by way of checking the scent, troops along with a pile of prayer books.
1895		Mirror of Life 4 May 10/3: [H]aving divested himself of his [...] upper Benjamin.
1896		A. Morrison Child of the Jago (1982) 128: The original out-and-out benjamins, or the celebrated bang-up kicksies, cut saucy, with artful buttons and a double fakement down the sides.
1904		Ade ‘The Fable of Another Brave Effort’ in True Bills 59: He is wearing the fawn-colored Benjamin with the Pearl Buttons, also the open-work Socks with the Monograms.
1909		J. Ware Passing Eng. of the Victorian Era 26/2: Benjamin (Maritime, 19 cent.). A sailor’s blue jacket, larger than the ‘monkey’ jacket which barely passes the hip-bones. It was the merciful invention of a Hebrew sailors’ tailor on Portsmouth Hard. The grateful tars appear to have given the name of this watcher of their winter comforts to the garment he invented. The word is now in general use for a jacket of dark-blue or black cloth made long and fitting to the figure. Generally called an ‘Upper Benjamin’. Sailors also call the rare nautical waistcoat a ‘Benjy’.
1924		G. Henderson Keys to Crookdom 397: Benjamin. An overcoat.
1931		‘English Und. Sl.’ in Variety 8 Apr. n.p.: In the Newgate or benjamine—Inside vest pocket.
1935		A.J. Pollock Und. Speaks.
1944		‘Jiver’s Bible’ in D. Burley Orig. Hbk of Harlem Jive.
1949		Monteleone Criminal Sl. (rev. edn).
1960, 1975		Wentworth & Flexner DAS.

2. an overcoat thief.

1909		‘The Lang. of Crooks’ in Wash. Post 20 June 4/2: [paraphrasing J. Sullivan] A flogger stiff or a Benjamin is an overcoat thief.
1919		Eve. World (NY) 1 May 30/6: Overcoat thief, ‘Benjamin’ or ‘flogger stiff’.