If you Mind Your Ps And Qs you behave in a correct and polite manner. There are two suggestions for phrase's origin. The first one is the French court during the 17th century. At this time, the aristocracy were expected to dance delicately when they took to the floor and so dance instructors were in high demand. During their lessons, they'd tell pupils to mind their "pieds" (feet) and "queues"(the tails of their wigs). The other suggestion comes from old London taverns. The bartender would keep track of how much beer customers had been drinking by marking their pints under the letter P and their quarts (two pints) under the letter Q. Customers would have to watch their Ps and Qs to make certain they weren't overcharged at the end of a session.