Posted by ESC on March 20, 2004
In Reply to: Ps and Qs posted by Kathy, Charlie, and Shannon on March 20, 2004
: Watch your Ps and Qs isn't listed on here, but I have been told that it means a long time ago bartenders made marks on the wall of how many pints and quarts were sold to keep track of them.
That's one theory. Several have been proposed here on Phrase Finder. If you'll click on the link below, it will take you to one discussion that lists several theories.