Remember "Emmet Otter's Jug Band Christmas"? It was a Jim Henson production that was shown on HBO back in 1981 (good god I'm getting old), and featured a band of otters that, well, had a jug band. It's all there in the title, folks. Anyway, there was some talent show that the otters needed to win, and seemed a cinch to do so, but fate threw a curveball at our wholesome heroes in the form of the Riverbottom Nightmare Band, a loud, sinister rock band that has a snake playing the guitar and a platform boot-wearing bear with the voice of Cookie Monster on keyboards.
One thing I really like about this clip is that the song that the Riverbottom Nightmare Band sings is about themselves. It's even called "Riverbottom Nightmare Band." This predates hip-hops obssession with self-referencing by a couple of years (or at least comes very close to tying "Rapper's Delight").
In particular, I urge you wait until until the 2:13 mark, when the frog creature playing the drums unleashes a blood-curdling shreik that really takes the song to new heights.