Cheats who throw themselves into the water, in order that they may be taken up by their accomplices, who carry them to one of the houses appointed by the Humane Society for the recovery of drowned persons, where they are rewarded by the society with a guinea each; and the supposed drowned persons, pretending he was driven to that extremity by great necessity, also frequently sent away with a contribution in his pocket.
Definition taken from The 1811 Dictionary of the Vulgar Tongue, originally by Francis Grose.
Queer Nab * Queer PrancerNathan Bailey's 1736 Dictionary of canting and thieving slang
John S. Farmer's collection of canting songs and slang rhymes