Depending on whether selling or buying, sellers or buyers use a ridiculously high, or ridiculously low opening offer that is not achievable. The theory is that the extreme offer makes the other party reevaluate their own opening offer and move close to the resistance point (as far as you are willing to go to reach an agreement). Another advantage is that the party giving the extreme demand appears more flexible when they make concessions toward a more reasonable outcome. A danger of this tactic is that the opposite party may think negotiating is a waste of time.