An old lady in a nursing home is wheeling up and down the halls in her wheelchair, making sounds like she's shifting gears in a car.  
As she's "driving" down the hall, an old man suddenly jumps out of a room, holds is arm out to stop the 'car' and says, "Excuse me ma'am, but you were speeding, can I see your driver's license?" She digs around in her purse a little, pulls out a candy wrapper, and hands it to him. He looks it over, gives her a warning, and sends her on her way.  Up and down the hall she zooms again.  And again, the same old man jumps out of his room, signals her to stop, and says, "Excuse me ma'am, but I saw you cross over the center line back there.  Can I see your registration, please?"  
She digs around her purse a little, pulls out a store receipt and hands it to him.  
He looks it over, gives her another warning, and sends her on her way.  
She speeds off again making even louder sounds and weaving all over the halls.
As she approaches the old man's room, once more he leaps out in front of the 'car', but this time he's stark naked and has an erection!  
The old lady in the wheelchair looks at the naked old man and shaking her head sadly, says, "Oh dear!  Not the Breathalyzer again!"