A middle school science teacher, Mrs. Parks, asked her class, "Which human body part increases to 10 times its size when stimulated?"

Little Mary stood up, angry, and said, "You should not be asking 6th graders a question like that! I'm going to tell my parents, and they will go and tell the principal, and you'll get fired!"She then sat back down.

Mrs. Parks ignored her, and asked the question again, "Which body part increases to 10 times its size when stimulated?"
"Anybody?" Finally, Billy stood up, looked around nervously, and said, "The body part that increases to 10 times its size when stimulated is the pupil of the eye." Mrs. Parks said, "Very good, Billy."

Then she turned to Mary and continued, "As for you, young lady, I have 3 things to say: 1st, you have a dirty mind. 2nd, you didn't read your homework. And 3rd, one day you are going to be VERY, VERY disappointed."