My friend had joined a weight-loss organization. At one meeting the instructor held up an apple and a candy bar. "What are the attributes of this apple," she asked, "and how do they relate to our diet?" "Low in calories" and"lots of fiber" were among the answers.

She then detailed what was wrong with eating candy, and concluded, "Apples are not only more healthful but also less expensive. Do you know I paid thirty-five cents for this candy bar?" They stared as she held aloft the forbidden treat.

From the back of the room a small voice spoke up: "I'll give you forty cents for it."