Ugh…thanks for the warning. Yookeroo. I think.
Also Homer kissing Hans Moleman brainwashed to think he’s Bart. “It’s like kissing a peanut!” Just odd. Very odd. And the mental image of Superintendent Chalmers wanting to make out with Edna- though, I agree, not in the league with CBG and Edna. And Homer’s ass scraping against the brand new roof of that other church- “Eyes on the floor, always always on God’s floor!” The scraping noise…
Arghh. I never got to see the arm-slicing episode. 
Hope they release Season 9 on DVD soon…
Audio: when Menthol Moose hocks up a giant flemwad. Much more effective without the visual. (I think it’s in the episode where Lisa wins a beauty pageant.)
Visual: in *Black Widower, when Selma asks Sideshow Bob to make love and pulls the bedsheet away. Yipe.
“Mmmm… Lemony fresh.”
“Homer, that’s liquid dish soap!”
“Yeah, well, what are you gonna do?”
The rat and the pigeon that get sewn together by Bart’s evil twin… It’s just not right
The only scene from the Simpsons that really disgusted me is when Homer is in the car after having laser eye surgery and his eyes crust all over.
I gag every time I see the RAT MILK episode.
Then there was the episode where Bart, uh, sat on the combination recliner/toilet with a newspaper.
Me too. But not as much as the arm-slicing or rat milk.
The grossest moments of the Simpsons (and I’d forgotten there were so many) disturb me more than anything on, say, South Park. Even the episode I think Yookeroo is referring to didn’t bother me – because that’s what I expect from South Park.
Based on this litany of abominations, maybe I should have expected the same from the Simpsons. Why did I ever think that piano wire would only cut the sandwich?
<Sideshow Bob voice> Brrrrrrrrrrr. </SBv>
Does anybody remember how Homer’s knee was hurt? Every time that episode’s comes on I always come in on the scene where he’s leaving the hospital.
Also, the episode where Homer wants to weigh 300 lbs. so he can get workman’s comp. Homer in a mumu… repetition of the Sideshow Bob voice.
Homer’s knee gets hurt when he tries a spectacular slamdunk during a pickup basketball game and gets his leg caught in the hoop. This wasn’t so bad, but then the backboard collapsed and crushed his knee.
I surprised no-one has yet mentioned the bit where Homer struggles with a vacuum cleaner and partly pulls out one of his eyes.
Unless you’re asking Homer. According to him, he was playing basketball in outer space when George Jetson hit him in the knee with his car. (He was heavy on morphine at the time.)
The knee scab healing over Ralph’s hand and the grease fight at the kids’ dance are definitely among the grossest.
Also Milhouse cleaning up the beach FULL of old syringes. He stuck himself on one and Skinner replied “Well, just keep going, one of them is bound to contain the antidote.”
What about Grandpa saying, “Sex? I had seeeexxxxx.”
Monty Burns wearing Homer’s brain as a hat: “Look at me, I’m Davy Crocket!”
Bart falls down the stairs and dislocates his arm, and they show it just hanging there, limply.
Lisa: "Eww! Your arm has extra corners!’
when homer is at a batting cage and he yells at the machine and a ball hits him in the finger… that makes my hand hurt
For some reason, the episode where Homer has a crayon removed from his brain and becomes intelligent freaks me out. When they shove the crayon back up his nose. ICK! BLEAH!
Hmmm, there are A LOT of episodes I haven’t seen.
I vote for when Cherry Bobbins (it IS “Bobbins” yes?) gets sucked into the jet engine.
On a slightly less icky note: the scene when Homer drinks an entire pickle jar full of brine. My spine wants to turn inside out just thinking about it.
Oh, and the scene in the Lemon Tree episode (my all-time favorite) where the Shelbyville dad takes a bite out of a lemon. (See above note about spine.)
But no, these aren’t as disgusting as springs in eyes or crayons up the nose.
I have to agree with Bart’s frog price in the “Harry Potter” haloween episode, though it did make for a funny line from Mrs.Krobople,
Mrs.K: Your sister is casting at a fifth grade level; you’ve sinned against nature.
In my list, the eyeball-spring thing is a close second to Homer’s eye after the vacuum hose gets caught on his face. Because that happens twice.
The scene where the school lunch lady is preparing lunch for the kids : “More bull testicles means more iron !”. She’s looking at a big cylinder labeled “Bull Testicles” as she says this, IIRC.