Where did the phrase "Mind your 'P's' and 'Q's'" come from?

Question

Where did the phrase "Mind your 'P's' and 'Q's'" come from?

Answer 1

There are a number of different stories about where this phrase originated from.  There's really no way to prove which is correct.  The one I can remember off the top of my head is that it originated in English pubs.  Patrons were told to mind their pints and quarts (of beer).  It was soon shortened to "mind your p's and q's".