One day in class the teacher...

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