http://dictionary.reference.com/search?q=nocebo&x=0&y=0

Main Entry: no·ce·bo
Pronunciation: "nO-'sE-(")bO
Function: noun
: a harmless substance that when taken by a patient is associated with harmful effects due to negative expectations or the psychological condition of the patient

Yes, it's the opposite of placebo. The great example I heard was on Penn Jillette's Friday the 13th podcast where Michael Goudeau told a tale of wishing a magician "Good Luck" backstage, and the magician getting so freaked out at how unlucky that is that he burned himself on stage about a minute later.

For some reason, I really like this word.

http://www.cnn.com/2006/WORLD/americas/07/24/bermuda.fisherman.ap/index.html?section=cnn_topstories

A fisherman was recovering from surgery after he was speared in the chest and knocked into the Atlantic Ocean by a blue marlin during a fishing competition off Bermuda's coast.