Thieves' Cant
From Delgar
Thieves' Cant is often described as a language, but it's more accurately called a cipher - that is, a code used to convey information covertly.
Thieves' Cant in this setting is a particular way of playing a common gambling game. It involves making specific plays and bets in combination with table banter, intentionally losing bets to pay for information, and so on.
