If you've heard of 1969's "musical Western" Paint Your Wagon, there's a decent chance you only know it from The Simpsons. In Season 9, Homer rents Paint Your Wagon for family movie night, hoping for a blood-and-guts western, as the picture stars Lee Marvin and Clint Eastwood, both known as men of violence. The Simpsonized version opens in media res, during what seems to be a tense showdown at high noon. Homer is disappointed when, instead of trying to kill each other, the cowboys break into a song of friendship. ("Gonna paint our wagon! Gonna paint it good!") It's very silly. But it's structurally sound. First it appears to be the prototypical western, then it pivots sharply into a middle-aged cartoon man's nightmare idea of what a musical is. There's a purity of form you have to admire. The actual movie Paint Your Wagon, on the other hand, is not like that at all.