Green’s Dictionary of Slang

(UK Und.) counterfeit money.

1810		York Herald 17 Mar. 2/4: Witnes then asked her if she had any Bobs or Shans; she said yes [...] and returned with four parcels of bad money.
1812		Vaux Vocab. of the Flash Lang.
1823		Egan Grose’s Classical Dict. of the Vulgar Tongue.
1906		A. McCormick Tinkler-Gypsies of Galloway 104: The following words appear to be still in use in one form or another amongst Galwegian tinkler-gypsies – Shand – Bad coin.