Classical mechanics Puns

Back in my classical mechanics class, we always used p to denote momentum, and q to denote position. Halfway through a lecture full of brain farts where everyone was accidentally saying and writing "p" when we meant "q" and vice versa, our prof said, "You gotta keep your p's and q's straight! Physicists know what it really means to mind your p's and q's." <<chuckles to himself>>