Saturday Night Live star Amy Poehler is quoted as saying, “Vanity is the death of comedy.” It’s a philosophy traditionally adopted by anyone seeking SNL breakout stardom, as it’s often the show’s broadest and most outrageous ideas that become fan favorites, regardless of —or perhaps because of — how it thrusts cast members’ guts, butts and other body parts right into the camera lens. For some SNL stars, it takes a little convincing. With the country flush with post-Olympics fever, the Nov. 19, 1977, episode of Saturday Night Live featured a commercial parodying then ubiquitous decathlon-winner…