Facebook now has some new “friends:” the United States Secret Service, thanks to a startling weekend poll appearing on the world’s largest social network that asked the question, “Should Obama be killed?” The poll provided four possible answers: “Yes,” “No,” “Maybe,” and “Yes if he cuts my healthcare.” Some 750 people had responded to the poll before Facebook members alerted the network and it removed the survey. Threatening the life of the president is a federal crime, so the Secret Service began its investigation Monday, and Facebook is cooperating with the agency.