If you wear 'togs', tell a 'yarn', call someone 'sly', or refuse to 'snitch' on a friend then you are talking like a convict.
These words, and hundreds of others, once left colonial magistrates baffled and police confused. So comprehensible to us today, the flash language of criminals and convicts had marine officer Watkin Tench complaining about the need for an interpreter in the colonial court. Luckily, by 1811, that man was at hand. James Hardy Vaux - conman, pickpocket, absconder and thief, born into comfortable circumstances in England - was so drawn to a life of crime he was transported to Australia ... not once, but three times! Vaux's talents, glibness and audacity were extraordinary, and perceiving an opportunity to ingratiate himself with authorities during his second sentence, he set about writing a dictionary of the criminal slang of the colony, which was recognised for its uniqueness and taken back to England to be published.