This cop is waiting outside a bar and sees this guy come stumbling out. The guy is staggering all over the sidewalk from the bar all the way to a car parked out front. The guy pulls out his keys, drops them, picks them up again, fumbles around trying to put the keys into the lock, finally unlocks the door, falls inside, starts the car, and drives away, weaving all over the road.
The cop turns on his lights and pulls the car over. The guy gets out and the cop gives him a breathalyser test.
The guy blows a zero-point-zero.
The cop looks at the results, then looks at the guy and asks, "What is this?
The guy straightens, looks the cop square in the eye, and says in a clear voice, "Tonight, I'm the designated decoy."
* Jokebook: Homeward Bound
* Jokebook: Police Phobia