If you're declared dead on twitter, it doesn't mean much anymore especially if you're Justin Bieber. But if a major bank declares you dead, that can really screw up your finances if you happen to still be alive. This happened to Arthur Livingston (who lives, oddly enough, in a town called Prosperity).
Bank of America reported him dead. Livingston only found this out when he tried to get a new mortgage. But no one would loan him money because he was supposed to be dead. It cost Livingston thousands of dollars to sort out the mistake. Bank of America has apologized, but of course, it hasn't offered him any compensation for its screw-up. Link: ABC News.