A blind man went into a restaurant and ordered a cup of coffee. When it arrived he complained that the coffee was not hot enough and requested a fresh cup. When it arrived he complained that it was the same cup. How did he know?
1. The cup did not have a crack or anything that distinguished it frm the other cups that were used in the restaurant.
2. He could not tell by the temperature of the cup.
3. He had not left a sticky mark or cream on the outside of the cup.