Green’s Dictionary of Slang

a silver sixpence.

[1784		J. O’Keeffe Young Quaker 6: I will give you a crooked Bit of Silver called a Six-pence].
1788		Grose Classical Dict. of the Vulgar Tongue (2nd edn).
1789		G. Parker Life’s Painter 178: Sixpence. A bender, crook, or cripple.
1796		Grose Classical Dict. of the Vulgar Tongue (3rd edn).
1811		Lex. Balatronicum.
1812		Vaux Vocab. of the Flash Lang.
1819		P. Egan Key to the Picture of the Fancy going to a Fight 34: ‘[A] bob, a crook, a duce, or even a mag will be acceptable’.
1823		Egan Grose’s Classical Dict. of the Vulgar Tongue.
c.1850		Duncombe New and Improved Flash Dict.