One day in class

One day in class the teacher has sex education.On the black board she draws
a penis then asks the class if any of them knows what it is.In the back of
the room,Dirty Johnny stands and says "That's a penis,and my father has two
of them". The teacher looks surprised and asks "What do you mean,two?"Dirty
Johnny responds,"A little one to pee,and a big one to brush the baby sitters
teeth."