Mark Twain's wife offered her children a bounty for dead flies and ended up with an indoor fly-breeding operation. This episode explores perverse incentives, reward structures that produce the opposite of what their designers intended, and the guiding principle known as Goodhart's law: when a measure becomes a target, it ceases to be a good measure. The hosts first examine the famous Cobra Effect and a 2025 investigation by the Friends of Snakes Society that found no archival evidence the cobra-breeding story ever happened.

Real cases follow: tailless rats in 1902 Hanoi, feral pigs at Fort Benning whose numbers rose because bait improved their nutrition, a 2021 sesame allergy law that led manufacturers to add sesame to plain buns, 3D-printed parts drained gun buyback budgets, and Alberta's mandatory reporting law that can silence witnesses. ...