In a mental institution a nurse walks into a room and sees a patient acting like he's driving a car.
The nurse asks him,"Charlie what are you doing?" And Charlie replies, "Driving to Chicago!" The nurse wishes him a good trip and leaves the room.
The next day the nurse enters Charlie's room just as he stops driving his imaginary car and asks, Well Charlie, how you doing?" Charlie says, "I just got into Chicago" Great," replied the nurse.
The nurse leaves Charlie's room and goes across the hall into Bob's room and finds Bob sitting on his bed masturbating vigorously.
With surprise she asks, "Bob what are you doing!" Bob says... "I'm screwing Charlie's wife while he's in Chicago!"