NYPD's failed Twitter campaign #MyNYPD is the latest example of an organization attempting to encourage goodwill on social media, only to discover that it invites uncensored responses. In November, JP Morgan invited Twitter users to participate in a Q&A session with one of its executives. The bank called it quits after seven hours of online vitriol. R&B singer R. Kelly and education reformer Michelle Rhee have also landed in their own version of social-media hell in recent months. Click through to read about their doomed attempts at Twitter chat.