Did everybody else already know this--the source, I mean?
sardonic (sahr-DON-ik) adjective

Marked by scorn, mockery, and cynicism.

[After Sardinia, a large island in the Mediterranean. Eating a Sardinian plant was believed to produce facial convulsions as if in a maniacal laughter.]

Are there any other words from illnesses that aren't used solely in descriptions of them? And, does anybody know what plant it was?