The hypothesis is advanced that sexual arousal and orgasm can result, in certain situations, from mental or physical violence or stress to oneself or to others. This sexual arousal is based in an organism's biological imperative to reproduce when under stress. Parallels with lower forms of life—cells, plants, and animals—are presented as demonstrating a unity of evolutionary purpose. Autoerotic asphyxia is looked at as a learned technique of enhancing sexual pleasure through hypoxia to the brain. Anaerobic exercise and the accompanying hypoxia is also presented as capable of inducing sexual arousal. Violence is examined as a sexual stimulus, especially as it occurs in sadomasochistic practices, rape, child molesting, and serial killings. All of these aberrant sexual behaviors are seen as stresses which can produce sexual arousal.