The bounty on dead cobras that supposedly left colonial Delhi with more cobras than before

According to a widely repeated story, colonial administrators in Delhi tried to cut the cobra population by paying a bounty for every dead snake — and enterprising residents responded by breeding cobras to cash in. When the bounty was scrapped, the breeders released their now-worthless snakes, leaving more cobras than before. Economists still cite it as the textbook case of a perverse incentive, though historians have found no contemporary records confirming it happened as told.

— Horst Siebert (coined the term in 2001); origin story's accuracy later questioned by historians, Der Kobra-Effekt: Wie man Irrwege der Wirtschaftspolitik vermeidet — 2001