You probably mean the "Cobra Effect", a form of perverse incentive[0]: The term "cobra effect" was coined by economist Horst Siebert based on an anecdote of an

You probably mean the "Cobra Effect", a form of perverse incentive[0]: The term "cobra effect" was coined by economist Horst Siebert based on an anecdote of an occurrence in India during British rule. The British government, concerned about the number of venomous cobras in Delhi, offered a bounty for every dead cobra. Initially, this was a successful strategy; large numbers of snakes were killed for the reward. Eventually, however, enterprising people began to breed cobras for the income. When the government became aware of this, the reward program was scrapped. When cobra breeders set their now-worthless snakes free, the wild cobra population further increased. [0]: https://en.wikipedia.org/wiki/Perverse_incentive https://en.wikipedia.org/wiki/Perverse_incentive