Just in case you don’t learn something new today.. One origin of the expression, “mind your Ps and Qs” comes from early printing presses. Printers placed individual letters on a frame to print a page of text. The letters were reversed, making it easy to mistake lowercase ps and qs in setting the type. Another origin comes from English pubs and taverns of the seventeenth century. Bartenders would keep a watch on the alcohol consumption of the patrons; keeping an eye on the pints and quarts that were consumed. As a reminder to the patrons, the bartender would recommend they “mind their Ps and Qs”. Now on to the gaps.