The revolutionary children's show hits the big four-oh this month, having launched on November 10, 1969, just in time for my two-and-a-half-year-old self to get in on the ground floor. To celebrate the occasion, Movieline has gathered clips of ten songs from the show, including abiding classics ("Sing") as well as pop satires such as the Beatlemanic "Letter B" and Madonnawannabe "Cereal Girl." Somehow, though, the editors left out what is for me, and I think many, the defining song of the show, and perhaps Jim Henson's career. Here it is, courtesy of songwriter Joe Raposo and history's classiest amphibian.