Thieves' Cant

Thieves' cant is the secret language of rogues. It is more of a cipher or jargon than an actual language. The main use of thieves' cant is to communicate rogue activities, such as banditry, burglary, finding marks, and discussing loot. It's also used for subtly finding work outside of the law and helping inform fellow rogues about the lay of the land.
Thieves' cant users rely on all manner of slang, innuendos, gibberish, code words, and phrases with double-meanings to convey messages through speech, and might also rely on subtle gestures and body language to supplement or emphasize these. Rogues have also developed an array of rudimentary symbols to alert one another, described in depth below.
Thieves cant isn't just limited to speech and iconography. Certain modes of dress and jewelry are often used to signify to other rogues that one is a member of the trades and what type of trade they engage in. Additionally, faux street magicians and gamblers might utilize decks of cards as a means of communicating rough messages and information about the local area with passing rogues, sometimes requiring coin for more information.
Thieves' cant cannot be learned without taking a rogue level, nor can it be understood or imitated by mortal magic.

Writing System

Written thieves' cant consists of a variety of cryptic symbols (akin to hobo signs) that are carved and chalked on walls and posts as graffiti to alert other rogues about important local information. Some examples of symbols include:

• A triangle with hands, signifying that a nearby resident is armed or has hired armed guards.
• A horizontal zigzag signifying a guard dog.
• A circle with two parallel arrows meaning "Get out fast".
• A cat signifying that a kind person lives here.
• A sideways horseshoe signifying that a place is not inhabited or guarded.
• Two overlapping circles marking that a fence is nearby.