Posted by Margo on February 23, 2001
In Reply to: Mind your P's and Q's posted by ESC on July 21, 2000
The origin is English, although I am unsure of the date. In English taverns when the gents would get hot under the collar after tossing back a few, the barkeep would admonish them to "Mind their p's and q's" -- pints and quarts, the serving sizes of ale.
In other words, let the argument go and get back to their drinks.