P's and Q's

[Mendacity]

My mom used to tell me this when I was young. "Make sure you mind your P's and Q's" but she could never explain what it means. My understanding it must mean mind your manners or be on your best behavior but what is the P + Q for?

Interesting board by the way and thanks in advance for any help. I'm sure its already been discussed but I didn't find anything with a search.

 

[Barb_D]

It means, "Make sure you pay attention to the details."

Here's one page that includes a few possible explanations of its origins:
Mind your Ps and Qs