"Our Thing" or "This Thing Of Ours". The real name for the Mafia. Cosa Nostra is a crime sydicate that began in Sicily in the mid nineteenth century. A "Made Man" is a man that has become a member of Cosa Nostra.
According to original Cosa Nostra rules, you had to be of Sicilian descent to be a member, you couldn't have a close relative that was a
police officer, etc. Many
political leaders have been murdered by Cosa Nostra.