Green’s Dictionary of Slang

(UK Und.) using a piece of whalebone daubed with an adhesive to rob a shop till.

1714

A. Smith Lives of Most Noted Highway-men, etc. I 261: The Whale-bone-Lay, which is, having a thin Piece of Whale-bone daub’d at the End with Bird-lime, then going into a Shop with a Pretence to buy something, whilst they make the Shop-keeper [...] to turn his back often, they then take the Opportunity of putting the Whale-bone so daub’d [...] into the Till of the Compter, which brings up any single Pieces of Money that sticks to it.