LOS ANGELES (AP) - Carrie Underwood gave a memorable performance of the Beatles' "Yesterday" at the Emmy Awards last night. Trouble is, many won't remember it fondly. Twitter users went nuts after Underwood performed the song during a tribute to two events that captivated TV audiences 50 years ago: Beatlemania and the assassination of President John F. Kennedy. After Don Cheadle introduced a series of clips, Underwood performed. And most tweets let her have it, saying the song was off key - and the tribute unnecessary. Tweeted Conan O'Brian show writer Sean O'Connor: "Some people never forget where they were when JFK got shot, but I will never forget where I was when Carrie Underwood murdered The Beatles."