Green’s Dictionary of Slang

a coin that has a false cover, which can be used or removed as required and which is used by cheats in games of coin tossing; Hotten (1874) notes: ‘This style of cheating is now obsolete. A man who cannot manage to cheat at tossing without machinery is a sorry rogue’.

1860		Hotten Dict. of Modern Sl. etc. (2nd edn).
1873		Sl. Dict.