We all know how genius “Kamp Krusty,” “A Streetcar Named Marge,” “Homer The Heretic,” “Itchy & Scratchy: The Movie” and “Mr. Plow” are, but even the relatively unheralded episodes offer wall-to-wall laughs and some of the smartest, darkest, and weirdest gags ever Trojan-horsed into a network cartoon with a massive family audience.