At closing time everyone come out and he spotted his potential quarry. The man was so obviously inebriated that he could barely walk. He stumbled around the parking lot for a few minutes, looking for his car.
After trying his keys on five other cars, he finally found his own vehicle. He sat in the car a good ten minutes, as the other patrons left. He turned his lights on, then off, wipers on, then off. He started to pull forward into the grass, then stopped.
Finally, when he was the last car, he pulled out onto the road and started to drive away.
The patrolman, waiting for this, turned on his lights and pulled the man over. He administered the breathalyzer test, and to his great surprise, the man blew a 0.00.
The patrolman was dumbfounded. "This equipment must be broken!" he exclaimed.
"I doubt it," said the man, "Tonight I am the designated decoy!"