Excerpt taken from the book The Story of French ( Ch. 8 )
The roots of argot go back as far as those of standard French. In the fifteenth century, Argot was the name of a crime syndicate of brigands, thieves and killers who spoke together in jargon (a deformation of the Norman word garg, throat). Jargon was not a language so much as a system of words that criminals used so they couldn’t be understood by anyone outside the group, in particular the bourgeois and aristocrats they robbed and the authorities who pursued them. By the seventeenth century the bourgeois referred to this criminal jargon as argot.
What is argot exactly? Semantically it is French, but argot borrows its vocabulary from regional and foreign languages and masks French words with suffixes. Roupiller (to slumber) is from Picardy; zigouiller (to kill) is from Poitiers; pognon (money) is from Lyon, and ringard (corny) is from a northern dialect. Loustic (rascal) is from German, gonzesse (girl) is from Italian, flouze (cash) and souk (disorder) are from Arabic, and berge (years of age) is Romany. Argot deforms standard French words with suffixes such as –iergue, -uche, -oche and -igue, which are the most common. So vous (you) in argot is vousiergue, and moi is mézigue.