Mr. Smith, a high school biology teacher, asked a student during class, “Barbara, would you please name the organ of the human body, which under the appropriate conditions, expands to six times its normal size, and define the conditions under which it does so?”
Barbara gasped, then stood up and said, “Mr. Smith, I do not think that is a proper question to ask me. I assure you, my parents will hear of this.” With that she sat down, blushing crimson.
Unperturbed, Mr. Smith called on Nancy and asked the same question.
“The pupil of the eye, in dim light,” said Nancy.
“Correct,” said Mr. Smith. “And now, Barbara, I have three things to say to you. One, you have not studied the lesson. Two, you have a dirty mind. And three, you are in for a big disappointment someday."