Perfect Behavior A Guide for Ladies and Gentlemen in all Social Crises by Donald Ogden Stewart

The first thing to do on arriving at a symphony concert is to express the wish that the orchestra will play Beethoven’s Fifth. If your companion then says “Fifth what?” you are safe with him for the rest of the evening; no metal can touch you. If, however, he says “So do I”–this is a danger signal and he may require careful handling.