A boy walks up to his dad and ask him, "Dad what is that thing between a girls legs that has hair on it?"
His dad said, "Well son that is called a vagina."
His son thought about that for a minute and then ask, "OK then, what is that little thing that looks like a really small penis in a woman's vagina?"
"Well they call that a clitoris son," said the father.
"OK dad, just one more question... What is that really smooth peice of skin that is below a woman's vagina?"
The boys dad thinks about this for a minute and says, "Well son, I don't know the medical term for it but I just call it a chin rest."