The Muppet Show - Season 5 Episode 14 Gene Kelly

Gene is under the impression that he's a "guest" -- that is, he's going to sit and watch, but not perform onstage. Frantic, Kermit tricks him into performing by asking him to give him a dance lesson on-stage. Kermit plans a surprise closing number, "Singin' in the Rain," Gene refuses, saying that he doesn't think he'll ever sing the song as good as he did in the movie, but he does eventually sing it backstage. Meanwhile, Scooter uses his Tarot cards to predict that the world is coming to an end. Beauregard believes him, and tries to convince the rest of the cast the apocalypse is near.