Green’s Dictionary of Slang

nob n.3

also nobb
[ety. unknown]

the game of prick-the-garter, a form of swindling game, in which one pricks a folded belt with a needle; the bettor attempts to pierce the place where the belt is folded.

[UK]J. Poulter Discoveries (1774) 7: We defrauded an old Farmer of fifteen Guineas, at the old Nobb, called Pricking the Belt.
[UK]Whole Art of Thieving 7: To shew how People are defrauded in Fairs and Markets, different ways, as follows: [...] Third, is the deceiving art, called the Old Nobb, that is, pricking in the belt.
[UK]G. Andrewes Dict. Sl. and Cant.
[UK]Flash Dict. in Sinks of London Laid Open 117: Nob, old, a favourite game used by sharpers, called pricking in the hat.

In compounds

nob pitcher (n.)

(UK Und.) a specialist in prick-the-garter, usu. working at fairs, races and similar open-air events.

[UK]Vaux Vocab. of the Flash Lang. in McLachlan (1964) 254: nob-pitchers a general term for those sharpers who attend at fairs, races, &c., to take in the flats at prick in the garter, cups and balls, and other similar artifices.
[UK]Egan Grose’s Classical Dict. of the Vulgar Tongue [as cit. 1812].