Souper problems

[Ginbottle]

A man returned his soup to the restaurent kitchen because there was a dead fly floating in it. The waiter returned with a bowl of soup; the diner was furious to know it was the same soup with the fly removed. How did he know?

[incitatus]

oh, a number of ways are possible here....lets start with: He left the spoon in it He ground pepper over the surface, which was still there later He had ordered the last bowl of soup and knew it He saw the waiter removing the fly and returning

[Dead_Meat]

Evidence of the surface tension being broken when the fly was removed?