A substance commonly used for Anaesthesia of animals and small children. Popularized by John Lilly as a psychoactive substance somewhat related to Phencycledine (PCP) in effect. In Timothy Leary's 8-circuit-model of consciousness this drug is associated with the 8th and highest circuit. Effects of a solid dose (particularly injected) include intense OOBE's (out of body experiences), Lilliputian hallucinations (feeling "as big as the universe" or "as small as an electron", often simultaneously) and other such psychedelic effects.
Jesus Christ, I think I took too much ketamine, I'm so deep in the hole I can hardly talk!