-- Directly thieved from Wikipedia. :)
According to reports, Clairvius was poisoned with a mixture of various natural poisons to simulate death. The instigator of the poisoning was alleged to be his brother, with whom he had quarreled over land. After his "death" and subsequent burial on May 2, 1962, his body was recovered and he was given a paste made from datura which at certain doses has a hallucinogenic effect and can cause memory loss. His new 'master', a bokor (sorcerer), then forced him, alongside many other zombie slaves, to work on a sugar plantation until the master's death in 1964. When the bokor died, and regular doses of the hallucinogen ceased, he eventually regained sanity (unlike many others who had suffered brain damage from being buried alive) and returned to his family after some time, though only after finding his brother had died. 
Narcisse's story was popularized in the book The Serpent and the Rainbow by Wade Davis, who is currently an "explorer in residence" for National Geographic. Although many are critical and suspicious of Mr. Davis' work, since his morals, as detailed in the book, prevented the necessary scientific experiments to prove his hypothesis that Clairvius Narcisse was drugged with a neurotoxin that simulates death, it is scientifically possible. The poison apparently used was derived from the puffer fish, which produces a well known and highly documented neurotoxin (tetrodotoxin) that produces paralysis and in modified form can mimic death through reduced metabolism and heart rate. The secretions of the poisonous cane toad Bufo marinus were apparently used as an anaesthetic companion drug, while the resuscitating, mind-controlling drug was said to be made from the weed Datura stramonium
And your vid of the day:
Kinda ridiculous. lol. Slightly not safe for work.