Outside a local neighborhood bar, a police patrol routinely parked outside on the weekends for the obvious reason that several of its patrons had the unfortunate habit of driving home inebriated. On this particular night, the officer noticed a man leaving the bar so intoxicated that he could barely walk. The man stumbled around the parking lot for a few minutes with the officer quietly observing.
After what seemed an eternity and trying his keys on five different vehicles, the man managed to find his own car which he fell into. He was there for a few minutes as a number of other patrons left the bar and drove off.
Finally he started the car, switched the wipers on and off (it was a dry night), flicked the hazard flasher on and off, tooted the horn, and then switched on the lights. He moved the vehicle forward a few inches, reversed a little, and then remained stationary for a few more minutes as more patrons left in their vehicles. At last he pulled out of the parking lot and started to drive slowly down the street.
The police officer, having patiently waited all this time, now started up his patrol car, put on the flashing lights, promptly pulled the man over and carried out a breathalyzer test. To his amazement, the breathalyzer indicated no evidence of the man having consumed alcohol at all!
Dumbfounded, the officer said, "I'll have to ask you to accompany me to the Police Station. This breathalyzer equipment must be broken."
"I doubt it," said the man, "Tonight, I'm the designated decoy."