Ethnic looking vendor in NYC: “We have Mountain Dew and crab juice”
Homer: “Yuck! Gimme a crab juice!”
When he was a missionary he sipped on a straw in something that looked like a coconut but was actually a wild boar testicle. When offered a coconut to replace it he refused.
Free Goo,
Right before that he ate something called crab kalosh or something like that.
The cat’s ear medicine.
A free sample of Lemon Time.
Hard to decide, the top ones in my opinion, in no particular order:
-Cats Ear Medicine from “Fly vs. Fly”
-The disgusting Sub sandwich with mushrooms growing on it(can’t remember which episode).
-The Hot Dog covered with filth from the Quik-e-mart from the episode where Apu gets fired and comes to live with the simpsons.
-Lenny, Carl, Moe and Apu, who have been turned into pigs by Circe in the Oddessy parody short. “This is the closet thing to eating lenny”.
The sandwhich was from the time Selma takes the kids to Duff Gardens, remember? Homer had been eating the sandwhich (he had taken it home from a picnic) again, and had food poisoning.
The gummy Venus de Milo that had been stuck to the babysitter’s ass.
The crab juice in NYC was a classic. What got me was how he grimaced when he first drank it… then knocked back the whole can… then ordered another!
Honorable mention (not eaten by Homer): the tongue sandwiches Thelma and Selma serve Bart and Lisa.
::shudder::
“Uggh…awwww…man, that’s good!”
Gots to get me some cat ear medicine. 
I can’t believe this hasn’t been mentioned, but he (kind of) ate God.
Homer: Why do you mock me, oh Lord!"
Marge: Homer, that’s not God, that’s just a waffle Bart threw up there. (knocks off with broom handle)
Homer: I know I shouldn’t eat thee…mmmm…sacrilicious.
Probably the food that had the worse effect on him was that pepper he ate at the chili festival.
And Pinchy was his friend.
It’s not disgusting to eat a lobster, but it’s a little disgusting to eat your pet.
The turkey’s a little dry. The turkey’s a little dry! Oh, foe, the cursed teeth! What demon from the depths of hell created thee?!
Liquid potato chips.
My vote still goes for a urnalcake.
I spelled that wrong, didn’t I…
But Pinchy would have wanted it that way.
What about when he got shock treatments and ate the rubber thing in his mouth?
“Homer, that’s just rubber and vasoline.”
“Marge, write that down so we can have it at home.”
Okay, so potato chips aren’t gross, but the reason he’s eating them is.
“Marge, I’d like to be alone with the sandwich…”
“Are you going to eat it?”
"…Yes.
That sandwich is probably the most disgusting thing he’s ever eaten. It was blackish-purple by the end. Oh, and the whole container of petroluem jelly. But the sandwich is the best.
Well, there was the time that he ate the fat from Bart’s steak.
Then in one episode he fantasized about eating the Quisp alien and drinking the Kool Aid Man. He’s also fantasized about eating animals while they’re still alive.
We also know that he eats the hot dogs which are strictly for ornamentation down at the Kwik-E-Mart.