Way back in the before-times of the internet — 1998 — I was in college. I took a class called “Film Appreciation”, and one of the students gave a presentation on how he believed Walt Disney had a butt fetish, evidenced by how often butts were hit, poked, or burned in Disney cartoons. I recently was talking about this in a Discord I’m in, and I wondered idly if there was any research on the topic.
Now, for those who don’t already know that Google is using Reddit posts to populate their AI search results, well… now you know. But to preclude that from happening I used DuckDuckGo’s search engine and input the phrase “walt disney butt fetish”, hoping for success. I found it on the second page of search results, from a site called “AllEars”. The article gives quite a broad representation of “rump humor” in Disney’s films and parks.

If you think about it, cartoons in general focus unduly on the butt. Hell, my core memory for spanking is a Tom & Jerry cartoon. Maybe not so much anymore — I don’t watch a lot of cartoons aimed at kids these days — but I distinctly remember it from when I was a young warthog.
Interestingly, it seems to be an American phenomenon; I’ve watched a lot of anime over the years, and even the sillier ones avoid specific butt-related humor. I mean, Ranma 1/2 is ripe for butt stuff, yet the only time butts are really focused on is when Happosai is leering at girls in their gym outfits. (And TBH I could absolutely do without Happosai in the show.) Embarrassing situations in Ranma tend to focus more on boobs. Just an observation.
I’m sure that, if you get down to it, the whole thing boils down to American (or Western) puritanism. I say Western because Walt Disney was Canadian, but Canada has many (though not all) of the same puritanical tendencies that America does, at least when it comes to nudity. Because butts are not to be shown, anything involving them is funny or erotic, even when it shouldn’t be. I mean, if someone poked you in the ass with a giant pitchfork or set your ass on fire that certainly wouldn’t be amusing, would it? But in Disney (and other) cartoons, serious injuries being done to butts are played for laughs. As for me, the only injury I want to see being done to butts is consensual spanking.