The 10 Best TV Guest Appearances of the Decade (2000-2009)

5. Cher on Will and Grace (2000)
Jack mistakes Cher for a drag queen and calls her “Mister Sister,” claming he does a better Cher than her. When she sings “If I Could Turn Back Time” to prove she’s the real thing, Jack tries to show her how it’s really done.
4. Oprah on 30 Rock (2009)
Liz Lemon takes sleeping pills and hallucinates an encounter with Oprah on an airplane. Starting the conversation with “I’m Liz Lemon and I lost my virginity at 25,” she goes on to confess that she eats emotionally and doesn’t like her feet, and complains that she didn’t get her September issue of O magazine. Turns out “Oprah” wasn’t really Oprah at all. She was just some random middle-schooler.