I noticed http://www.quinion.com/words/articles/psandqs.htm

I 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.


k