What's the origin of the phrase mind your P's and Q's? Why those two particular letters, rather than (say) "mind your ABC's"?
it refers to your please and thankyous, your manners
Two different candidates to far.
I too have heard of it as Pints and Quarts: it was important for sailors going on shore leave to be careful with them (mind them) because Press Gangs were about, and if you were too drunk to know what was going on you might wake up to find yourself crewing on a strange ship for a couple of unintended years...
I noticed
http://www.quinion.com/words/articles/psandqs.htmI remember I first heard the phrase from Mr Sipes (10th grade algebra II) who had just given us the proof that sqrt(2) was prime (check out
http://www.albanyconsort.com/theorems/theorems.html about 1/2 a page down) and then stated that the phrase mind your ps and qs referred to that. I guessed he was kidding at the time, but wasn't sure until some years later.
I don't recall every hearing the phrase used in conversation, but I have an extremely vague idea that I might have heard it spoken in a movie at some point.
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