At the local hospital for the mentally unstable, a nurse goes into Bob's room to find him sitting up in bed with his arms outstretched, moving them like he's driving a car.
She asks, "Bob, what are you doing" ?
"I'm driving to Chicago", he replies.
"Oh . . . okay", she says, and leaves the room.
The next day, she goes into Bob's room and finds him sitting up in bed doing the same thing.
She asks him, "How are you doing, Bob"?
"Just fine. I'm pulling into Chicago right now."
She just smiles and leaves.
She then goes into Bill's room, across the hall and finds him sitting up in bed masterbating.
"BILL ! WHAT are you doing ?" she bellows.
Bill just chuckles and says, "I'm screwing Bob's wife while he's in Chicago !"