[scythe]

For one thing, we enjoy sharing the story, which is a useful cultural trend because it causes us to spread information about dangerous events and prevent people from being injured in the future. This is not quite as accurate as scientific data, but it can take advantage of neural circuitry which is not useful for science.

For another, it promotes a sense of shared identity of rule-followers, by criticizing people who break rules, which promotes pride in following rules and prevents people from breaking them. This is important because when I read a sign telling me to do something it is necessary that I trust the person who wrote the sign if I am to obey.

But like all forms of humorous entertainment it is not as amusing when we deliberate on it for too long. And there is a pernicious feedback effect of callousness which can arise from the sense of collective identity mentioned in the second paragraph. The positive effects of such activities seem to be best utilized when many cultural mores are practiced together to smooth out the "errors".