I've alway been fascinated by cants, cryptolects and slangs. Recently I've been thinking about how cants are used in ttrpgs - so I've been having a look at some texts such as the 1811 Dictionary of the Vulgar Tongue.

It claims to be a list of all possible rogues and con-men from the time and the slang they used. It also has some wonderfully opaque definitions such as:

"CROAKERS. Forestallers, called also Kidders and Tranters."