The postman hardly looked puzzled. People working at the Grand Central Post Office grow used to strange remarks. They hear so many. (from The Mixed Up Files of Mrs. Basil E Frankweiler by EL Konigsburg)
I feel like this quote is true of people who use public transportation as well. If you’re on the bus with someone you don’t notice. But if you’re riding alone, you hear some really wild conversations, most of which you have no context for and only hear snippets of, which of course makes them so much funnier.