Orgasm is a reflex of the autonomic nervous system. Now, this is the part of the nervous system that deals with the things that we don't consciously control, like digestion, heart rate and sexual arousal. And the orgasm reflex can be triggered by a surprisingly broad range of input. Genital stimulation. Duh. But also, Kinsey interviewed a woman who could be brought to orgasm by having someone stroke her eyebrow. People with spinal cord injuries, like paraplegias, quadriplegias, will often develop a very, very sensitive area right above the level of their injury, wherever that is. There is such a thing as a knee orgasm in the literature.