When being closely followed by a vehicle, a driver may adjust his or her speed to closely match that of a secondary car in the next lane, creating a barricade which closes any opprotunity for the impatient tailgater to pass. This strategy is especially effective if the follower has ignored the brake-tapping warning, and there has been plenty of time and opprotunity for the following vehicle to change lanes and pass. The intending purpose of which is to encourage the folling vehicle to fall back and ease off the tailgating, and to give the tailgated driver a sense of passive-aggressive revenge. A lack of cooperation from the secondary vehicle, or a two-lane freeway expanding into a three-lane may lead to a failure in which the barricade is broken and the tailgater is able to get by.
You need to tailgate barricade. He'll get the idea!