Keep the Change
Selling secondhand books at our church bazaar, I got into an argument with a prospective customer. He was interested in buying The Pocket Book of Ogden Nash but claimed it was overpriced at 35 cents. Other paperbacks were selling for ten or 15 cents each.
I pointed out that the book was in good condition. Nash was a fun poet, and it was for a good cause. He said it was a matter of principle. Ultimately, I agreed to sell him the book for 15 cents. Triumphant, he paid with a $10 bill. "Keep the change," he said.