The Possum Experiment is a recent episode of This American Life about a woman who posts a sign in her neighborhood as a joke that says "cat found." The flier features a photo of what is clearly a possum. Then, the unexpected happens: An overwhelming number of people call in and believe that her sign is completely serious. Others scold her for not knowing the difference between a cat and a possum. Her joke was lost on these folks, and their responses "ultimately shift her view on humanity".