Notoriously rowdy bar

A funn joke for yu!Enjoy it:

Staking out a notoriously rowdy bar for possible D.U.I. violators, a cop watched from his squad car as a fellow stumbled out the door, tripped on the curb and tried 45 cars before opening the door to his own and falling asleep on the front seat.
One by one, the drivers of the other cars drove off. Finally, the sleeper woke up, started his car and began to leave. The cop pulled him over and administered a Breathalyzer test. When the results showed a 0.0 blood-alcohol level, the puzzled policeman asked him how that was possible.
"Easy," was the reply."Tonight was my turn to be the decoy"