Dr Parker, the biology instructor at a posh suburban girl’s junior college, said during class, “Miss Smith, 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.”

Miss Smith gasped, blushed deeply, then said freezingly, “Dr Parker, I do not think that is a proper question to ask me, you should be asking a boy. And I assure you my parents will hear of this.”

With that she sat down, very red-faced.

Unperturbed, Dr Parker called on Miss Johnson and asked the same question. Miss Johnson, with composure, replied, “The pupil of the eye, in dim light.”

“Correct,” said Dr Parker. “And now, Miss Smith, I have three things to say to you.

One, you have not studied your lesson.

Two, you have a dirty mind.

And three, you will someday be faced with a dreadful disappointment.”