A man stumbles out of a bar one night obviously drunk. He makes his way down the street knocking into everything in his path. A police officer watches him from a cruiser across the street. The man comes up to a parked car, fumbles around in his pockets, gets his keys, and proceeds to drive away. The police officer, unbelieving what he saw, pulls the man over a few blocks down the road. The man gives a breathalizer for the officer and to the officers amazement – the guy was stone cold sober.

I cant belive it! I watched you walk to this car, drive erratic all the way down the road, and my machine says you have no alcohol in your system! How can that be???

Oh thats easy, replies the man.

Tonight Im the designated decoy.