Punishment in humans is emblematically promiscuous. We castigate others whenever they violate a social norm, in both competitive and cooperative situations, targeting kin and non-kin. Punishment is doled out by the individual directly harmed and also by third party onlookers. We use both physical and non-physical means to discipline cheaters, including ostracism. Punishment’s landscape is vast. The idea I develop here, building on the work of scholars in economics, psychology, and anthropology, is that our species alone circumvented the costs of punishment as an incidental consequence of promiscuity, including an intimate coupling between the systems of aggression and reward. As several brain imaging studies reveal, when we either anticipate or actually punish another, or even witness punishment as a mere bystander, our reward circuitry delivers a honey hit. Delivering just deserts, or watching them delivered, is like eating dessert. We absorb the costs of punishment by feeling good about ratting out the scourges, banishing them from society, and sometimes from life itself. Ironically, as the economist Samuel Bowles has suggested based on mathematical models and a synthesis of the historical record, punishment can strengthen solidarity and cooperation within the group, while simultaneously enhancing antagonism and prejudice toward those outside the inner sanctum. Ironically, the psychology that benefited cooperation among like-minded others may also have functioned to destroy those who have different beliefs and values. The emergence of promiscuous punishment was a momentous event in human history, a celebration of exquisite brain evolution and adaptive design. But this achievement carried a hidden cost, a debt that we continue to pay: A mind capable of feeling good about punishing in the name of virtue is a mind capable of doing bad to feel good. It is a mind that finds real or simulated violence entertaining and seeks ways to satisfy this interest. It is a mind