You are driving your car down some street or on a freeway. Up ahead, stop lights are coming on. You notice that little, orange cones are beginning to appear; a large, yellow arrow is flashing, indicating that the lane you are in will soon merge into the lane to your left.
Being a good driver, you immediately nose your vehicle over, into the lane directly to your left, since this will be the "through" lane. Most of the other vehicles in front of you are doing the same thing.
As a result of this, two things begin to happen: (1) cars begin to jam up in the through lane and (2) an open space begins to develop in the lane that is going to close up ahead.
Enter, at this point, The Jerk. Knowing full well that a lane merger is taking place ahead, The Jerk's car drives happily up to the point of merger, passing dozens of other, good drivers who have already merged into the through lane. You, and the other motorists who have all done that they were supposed to do, are then treated to the sight of some "nice guy" up ahead letting The Jerk in at the point of merger. Rarely does The Jerk have to wait more than one or two cars before being let in.