4. Ashlee Simpson
The operative word is Saturday Night Live. But apparently Ashlee Simpson didn’t get the memo when she appeared on the long-running sketch comedy series. Jessica’s younger sister was all set to sing her title-album track “Autobiography,” but instead the words and music to “Pieces of Me”—which was performed earlier during the show—were pumped from the speakers. At that point, a closed mouth Ashlee broke into an impromptu square dance as the program abruptly cut to commercial. "I feel so bad," Simpson said during an interview following the jaw-dropping broadcast. "My band started playing the wrong song. I didn't know what to do, so I thought I'd do a hoedown.” Brilliant.