The teacher asks, "Jessica, what part of the human body increases ten times when excited?"
Jessica blushes and says, "That's disgusting, I won't even answer that question."

The teacher calls on Johnny: "What part of the human body increases ten times when excited?"
"That's easy," says Johnny. "It's the pupil of the eye."

"Very good, Johnny," responds the teacher. "That's correct."
She then turns to Jessica and says, "First, you didn't made your homework. Second, you have a dirty mind. And third, you're in for a BIG disappointment."