What's a weird saying?
When examined, or just because it's weird on its own.
Example: Beat a dead horse
Mind your ps and qs. What are ps and qs?
I know there are lots of possible origins for this phrase, but I think of it as "pleases" and "thank yous". The "k" sound from "thank" followed by the word "you" combine to sound like the letter q.
I've heard that it means pints and quarts, referring to beers. I feel like I've also heard it was a typesetter thing.
The typesetter one makes so much sense, since handling mirror images of letter you will definitely get your p and q mixed up.
The Wikipedia entry on that one is a fun read. I've heard most of these possible origins before, but nobody is actually sure of the true origin of the phrase. It's kind of frustrating, but also pretty neat that we still use a phrase long after we forgot where it came from.
It's not a common saying here and I assumed it meant to pay attention to detail, be meticulous and precise, like "dot the i’s and cross the t’s". 'p' and 'q' can be written similarly.