There's a difficult one about albatross soup, which wouldn't really work with chicken soup. But here's an easier one about any kind of soup, which you could transmute into chicken soup if you wanted to. Question - A man in a restaurant returned his soup because there was a fly in it. The waiter brought him a supposedy fresh bowl of soup, but the man refused it because it was exactly the same soup, with the fly taken out. How did he know? Answer - Because he'd put salt in his soup before he sent it back, and the "fresh" soup tasted salty.