The 10th grade teacher asks Jessica: "What part of the human body increases to 10 times it's normal size when excited?"
Jessica responds: "That's disgusting! I don't have to answer that question!"
So the teacher asks little Johnny.
Johnny responds: "That's easy…the pupil of the eye."
"That's correct Johnny. Very Good!"
And turning to Jessica, she says: "I've three things to say to you, young lady…first, you didn't do your homework; second, you have a dirty mind; and third, you're in for a big disappointment."