Yet, the time needed to split the check is already lost from his point of view, along with the extra tip he might have received form the next table. At that point, annoying the customer is simply irrational behavior: she loses even more money only to make a point, knowing that the customer will retort to what you call shitty behavior to make the point back.<p>While typically irrational for the individual, anger can be rational for the selfish gene, thus be preserved in the species: angry bees are avoided by other animals even if individual bees are suicidal, thus making the suicide of an individual work for the group.<p>So whenever you feel the need to go on a rampage destroying yourself along with your archenemy, you should really ask yourself if you are still in control, or you are executing out a program developed 1 million years ago and designed to protect the occupants of your cave from attacks of rival hominids, even at the price of your life.