John is driving home after downing a few at the local pub. He turns a corner and much to his horror he sees a tree in the middle of the road. He swerves to avoid it and almost too late realizes that there is yet another tree directly in his path. He swerves again and discovers that his drive home has turned into a slalom course, causing him to veer from side to side to avoid all the trees.
Moments later he hears the sound of a police siren and brings his car to a stop. The officer approaches John’s car and asks him what on earth he was doing.
John tells his story of the trees in the road when the officer stops him mid sentence and says,
"Fer heaven’s sakes, John, that's yer air freshener!"