A teacher was reviewing her class’s homework assignment.
She asked Susie to stand up and tell the class what part
of the human body enlarges to seven times its original
size when stimulated.
Susie stood up, shuffled her feet and said, “Well, I think
I know, but I’m too embarrassed to tell you.”

The teacher said, “Sit down, Susie. Johnny, tell the class
what part of the human body enlarges to seven times its
size when stimulated.”

Johnny said, “That’s easy. The pupil of the eye enlarges to
seven times its original size when stimulated by light.”

The teacher said, “That’s right, Johnny.” Then she turned to
Susie and said, “Susie, first of all, you didn’t do your
homework. Second, you have a dirty mind. And third, when you
get married, you’re in for a big disappointment.”