I would have to say the nastiest thing I ever had the misfortune to eat was a type of German potato salad. To my uninformed white trash eyes, it looked like warm, buttery mashed potatoes. However, it tasted like cold, vinegary, rancid death. That, and one of my fraternity brothers switching my bottle full of Dr. Pepper for his bottle full of dip spit. It's ok, though. I poured his dip spit all over his brand new New Balance shoes. After I puked.
Being from Minnesota, Norwegian, and Lutheran, there is one answer here: Lutefisk. For some reason, my grandparents absolutely love this shit. Even thinking about it right now I am beginning to gag. I think the picture from Wikipedia says it all.
Last year at college, during the middle of the winter, I was just about out of food. I had no car, so I was reliant on friends' rides to get groceries (I could walk the several miles when it was above zero). I noticed that I had some ground beef in the back of my fridge. It had been in there no less than two weeks, and was nearly entirely gray. It didn't smell too bad, so I decided to see how it would taste when I cooked it. It didn't taste too off, so I added some extra ketchup/spices to cover its taste. What a mistake. About a half hour after I finished the three burgers I'd cooked, a sense of impending doom came over me. I resigned myself to my fate, went to the bathroom, and settled in for what was sure to be a long stay. What followed was the most mentally exhausting three hours of my life. Every time I thought I was empty and left the bathroom, I wouldn't make it ten steps out before sprinting back in. I'd never felt as drained, nor have I since. Long story short, don't eat gray meat.
I lost a bet in culinary school where I had to eat a "cake" that was made from chewing tobacco (used).
I was at a titty bar once with a buddy who dipped. He was using some empty plastic cup to slosh his spit in, when who appears to dance on our table? The main dancer of the night. She's in front of us on the table dancing around, being sexy and what not. Without looking she drops down, picks up his spit cup, sticks her fingers in it and drips the chew spit all over her $10,000 dollar rack. I'm assuming she thought there was alcohol in the plastic cup and we would lavish more money on her for dousing herself in an $8 dollar drink. Instead she got my buddy's nasty chew spit all over her. We didn't get to see the rest of her show.
Shots of apple cider vinegar.. for ambiguous health benefits. You get used to it after a while but... randoms think you're weird when they see you chugging vinegar out of the bottle.
I got dared to eat an apple, core and all, for $10. It tasted exactly the same and I can now turn an apple into a meal by eating it. Call me a weirdo, I guess.
Marmite is amazing. A particular favourite is marmite and jam (jelly for you yanks). It's like a sweet and sour type thing. The only problem is I think it might be like cricket - if you grow up with it you love it and if you don't you hate it. I mean, their entire marketing campaign is "You either love it or hate it". Worst thing I ever ate was fuck loads of raw pasta when I was about 4. My Dad was making pasta fresh and I stole a load off the table and ate it. My chronic pains etc. meant that my parents didnt feel any need to punish me though.
Do snails count? This summer I ate a snail, I'm not sure how they cook them, but I think they boil them. This was the first time I ate a snail so I expected the snail to be soft and slimy but it was chewy and quite tough. They add a lot of herbs and spices to the snails, so they taste like, well herbs and spices.
Well there was this girl I was dating once... Seriously though, when we were younger we had a kid from Vietnam who used to hang around with us, he was a trip. We tool a polite young man from Southeast Asia and Americanized him properly. Few funnier things in the world than a Vietnamese kid uttering, " Muddafucka". Anyhow, he would cook us some crazy shit he grew up on, and one night we joked about eating dogs and cats. I'd like to say in hindsight that we laughed, cracked open another beer and went on with the general bullshit we were up to that night. Instead, I can tell you it was spicy, tender and delicious.
I used to own a couple pet rats. One day I had one out to give it some exercise, and to reward it for not being a little rodent bastard who deserves to be thrown in the drier, I gave it a small chunk of watermelon. Which it failed to finish. So I did, in front of my family. Yeah. I once ate a piece of watermelon double-dipped by a rat. Beat that.
A Mexican Hooker. I mean, the vagina was alright, but once you start ingesting the rest of her there's just so much hair and well, needless to say the highway interstate has a new bff.
Dude poi is fucking delicious and so is goat. For me it was vegemite on toast. Most disgusting rancid shit I've ever smelled, let alone eaten.
Spam. Like ground up guts and anuses, hot dog water, spit, and fetid puss mixed into a gelatinous cube of shitfuck. Don't even think about cooking it a little. That just makes it angry. I've been flirting with offal. I've heard your best bet is to start small, start safe. Fried bits, stuff drenched in sauces. Anything that will help mask that gamy, borderline rancid flavor. The Brits suck down steak and kidney pie all the time. I had it when I was over there years ago. I recall it being pretty enjoyable. When I did homemade steak and kidney pie, those pointers didn't help at all. Even simmered in wine the beef kidneys had the texture of vulcanized rubber. They tasted like a petting zoo smelled. The fucking cats wouldn't even touch it.
I think Marmite is delicious, who wouldn't want to spread left over brewer's yeast on a piece of toast for breakfast. Focus: A huhu grub. It was soaked in Whiskey but it was still pretty gross.
Falafel. Chickpeas? Absolutely disgusting. I wish I could have aborted my stomach afterward. There are some foods you pray AFTER you eat.