Green’s Dictionary of Slang

1. a small eating-house or restaurant where one pays on receipt of the food, rather than eating then receiving a bill; also attrib.

c.1786		Grose Classical Dict. of the Vulgar Tongue ms. additions n.p.: Slap-bang Shop. A Petty Cook’s shop, where there is no Credit, but what is had must be paid for down with the Ready slap-bang, i.e. quickly. This is a common appellation for a Night cellar frequented by Thieves &c. Also a name for a Stage Vehicle.
1788, 1796		Grose Classical Dict. of the Vulgar Tongue (2nd, 3rd edn) n.p.: Slap-bang Shop. A petty cook’s shop, where there is no credit given, but what is had must be paid down with the ready slap-bang, i.e. immediately. This is a common appellation for a night cellar frequented by thieves, and sometimes for a stage coach or caravan.
1811		Lex. Balatronicum [as cit. 1788].
1824		J. Wight Mornings in Bow St. 22: I vaulks myself to a slap bang shop, for a half a pound o'beef; and just as I'd got it up, to pop in the first bit, a voman, vaut I nows nothin on, comes behind me and vips it off the fork.
1826		Pierce Egan’s Life in London 1 Jan. 390/1: Mary Gahagan is hand-maiden at the celebrated Clare-court slap-bangery, where gentlemen of large appetite and little means get themselves handsomely stuffed with boiled beef and its vegetable concomitants at a very trifling expense.
1836		N.Y. Herald 16 June 1/2: Choice way of creating an appetite, and getting a cheap dinner. — Go to Sandy Welsh’s between the hours of 2 and 4, glance over the bill of fare, snuff up the odoriferous scent from the luxuries and delicacies of his kitchen, take three turns round, and then dart into Sweeney’s slap bang shop.
1840		London Mag. Feb. 12/1: [T]hat celebrated ‘slap-bang,’ or cut-slice eating-house [...] the ‘Larder of the Universe, Leg-of- Beef Soup, and general Roaste and Biled Establishment’.
1846		Glasgow Herald 20 Apr. 2/1: The turning of the Hall of Congress into a chop-house or ‘slap-bang’ shop is [etc.].
1850		Bell’s Life in Sydney 16 Mar. 3/3: The proprietor of a Slap-bangian and all-sorts-of-thingian repostory.
1857		‘Ducange Anglicus’ Vulgar Tongue 2: Ben-Flake, n. A steak, used at a slap-bang, i.e. a low cook-shop or eating house.
1859		Hotten Dict. of Modern Sl. etc. 95: SLAP BANG SHOPS, low eating houses, where you have to pay down ready money with a slap bang.
1861		(con. 1840s–50s) H. Mayhew London Labour and London Poor IV 426/1: My brother [...] got to clean knives and forks at a slap-bang (an eating house) in the city.
1865		G.A. Sala My Diary in America II 235: [The] desire on the part of the English noblemen and gentlemen to become tapsters and slap-bang shopkeepers.
1870		Hotten Sl. Dict. [as cit. 1859].
1879		Nat. Police Gaz. (NY) 13 Dec. 14/4: The American slap-dash restaurant, with its fifteen cent meats, is too well known to need description.
1880		S.A. Mackeever, Glimpses of Gotham and City Characters 29/2: [as 1879].
1895		Crowe Aus. Sl. Dict. 75: Slap-bang Shops, rough eating houses, or a refreshment saloon where everything is done hurriedly.

2. in attrib. used of sense 1.

1866

Letters by an Odd Boy 199: People [...] inadvertently express their admiration for the dog in a certain ‘Slap bang’ chorus to be heard everywhere, every day, all day long?