“I’m so funny! This is gonna be great!” – Homer Simpson
“What are you doing?” – Marge Simpson
“I’m writing a delicious send up of Mr. Burns for his birthday party. Is “poo-poo” one word or two?” – Homer Simpson
The Simpsons wouldn’t be what it is without the acting, the animation, the music, the sound effects, and everything else, but ultimately it all derives from the writing, and the writing on the show was as finely honed as any artistic masterpiece. Consider this brief stretch of dialog from “Rosebud”:
Homer: “Ow. Where did I lose ’em? I’ll never wiggle my bare butt in public again.”
Lisa: “I’d like to believe that this time, I really would.”
Marge: “Bart, run down to the store and get a big bag of ice for your father.”
Bart: “Yes’m. Dad, I know you’re discouraged, but please don’t deny the world your fat can.”
Homer: “Don’t worry, boy, she’ll be ready for your Aunt Selma’s birthday.”
Lisa: “I knew it.”
If this exchange isn’t taught in screenwriting classes, it should be. The jokes start in the first line because Homer didn’t “lose” his audience, he never had them in the first place. (Going on after an announcement about the death of a small puppy, not unlike Lassie, will do that.)
From there Homer, profoundly dejected, declares that he’s going to keep his “bare butt” private from now on. Lisa’s response is three punchlines in one: 1) “like to believe”, because she clearly doesn’t, 2) “this time”, which means Homer has promised to stop showing his butt to strangers multiple times before, and 3) “I really would”, the resigned, melancholy sincerity of this means that not only does she not believe him, she’s so numb from being let down in the past that she can’t bring herself to believe her father even a little.
Look how sad she is.
The next line is Marge advancing the plot (a/k/a exposition) which the show seamlessly blends in with the jokes. It fits snugly both with Marge’s character and the immediate situation. This kind of routine, quick, and sensible story advancement is totally beyond Zombie Simpsons.
Bart gives his mother a smarmy “Yessum”, as though he routinely does errands with no objection, and then immediately tries to cheer Homer up by telling him not to be “discouraged” about mooning strangers. Note that he doesn’t say it directly or even crudely, his appeal to Homer is downright noble in its phrasing: to not “deny the world” Homer’s “fat can”. Bart finds Homer’s ass as sincerely hilarious as Lisa finds it mortifying, and the wording perfectly conveys that without so much as a wasted syllable or stray modifier.
Look how genuinely supportive Bart is of Homer’s penchant for mooning. It’s endearingly funny.
Because of that setup, Homer’s response can work on two levels: first, he instantly cheers up because, like Bart, Homer finds “wiggling his bare butt” in public to be the height of humor. He’s almost gleeful about it. Second, despite his earlier declaration to stop, he’s already got his next act of public nudity planned for his despised sister-in-law’s birthday.
Finally, the scene ends with a callback to Lisa’s multi-punchline from fifteen seconds earlier. The simple “I knew it” confirms her earlier skepticism, so not only did Lisa not believe her father, it becomes even funnier because she was right to do so.
The entire scene is less than thirty seconds long and contains only six lines of dialogue, but it moves the story along, shows off the entire family, and is packed not just with jokes, but with layered jokes. Scenes like this are a big part of why the show is so endlessly rewatchable: no screen time is ever wasted, and anything that can be funny is funny.