Fifty years ago, as it turns out, according to the UK Telegraph:
In 1951, a quiet, picturesque village in southern France was suddenly and mysteriously struck down with mass insanity and hallucinations. At least five people died, dozens were interned in asylums and hundreds afflicted.
For decades it was assumed that the local bread had been unwittingly poisoned with a psychedelic mould. Now, however, an American investigative journalist has uncovered evidence suggesting the CIA peppered local food with the hallucinogenic drug LSD as part of a mind control experiment at the height of the Cold War.
Just something to think about for those who reflexively assume government agent's never do insanely unprovoked and irresponsible criminal acts. More details in the full story.
UPDATE: Author of a book on the French bread panic, Stephen Kaplan, thinks the CIA story doesn't hold up, with more details on the CIA' acid interests. At least two of Kaplan's points don't make sense–first of all, LSD is not at all highly toxic as he states, and baked goods are a perfectly common means of holding a liquid suspension of the drug, incredibly powerful at small doses. If he is correct in stating that the effects didn't kick in til a day or more after eating the supposedly laced bread, that is a telling point against the "dosed" theory.
UPDATE II: The evidence and arguments of commenter Anon in the comment thread below–more thorough and better reasoned than those of Kaplan as excerpted in the above link–convince me that the Telegraph story linked above is not true. But keep the discussion going!