2nd Edition Player's Handbook wrote:Thieves' Cant: Thieves' cant is a special form of communication known by all thieves and their associates. It is not a distinct language; it consists of slang words and implied meanings that can be worked into any language. The vocabulary of thieves' cant limits its use to discussing things that Interest thieves: stolen loot, easy marks, breaking and entering, mugging, confidence games, and the like. It is not a language, however. Two thieves cannot communicate via thieves' cant unless they know a common language. The cant is useful, however, for identifying fellow cads and bounders by slipping a few tidbits of lingo Into a normal conversation.
The concept of thieves' cant is historical (the cant probably is still used today in one form or another.) although in the AD&D game it has an ahistorically broad base. A few hours of research at a large library should turn up actual examles of old thieves' cant for those who want to learn more about the subject.
