[laughing with you not at you]
Hahahah…ha 
[/ok…maybe I’m laughing at you, just a little, but only because it wasn’t me]
That’s exactly what I was going to mention. Don’t people know that there is only one way to peel bananas?
Well you should have. You cannot let such abominations pass. Clearly Bulgaria needs to be taught a lesson. 
In Italy you would be looked at askance if you were you cut your pizza into triangles and eat them by hand. A pizza is an individual-serving dish that is eaten by cutting off one bite at a time (unless you’re eating from a street vendor on the streets of Naples).
But to the OP–it doesn’t bother me if “the wrong way” is specific to the food as opposed to basic manners. It doesn’t bother me if someone eats french fries with their fingers in a nice restaurant, as long as they chew it with their mouth closed.
On a trip to England, my host and I were eating bananas at his home. I peeled back the banana and take a bite of the exposed portion. My English friend was peeling it back, then grasping the top of the exposed portion, breaking off a section, then eating it out of his hand. I made the mistake of asking why he would do that, when if he used my style he wouldn’t have to touch the fruit with his hand. He referred to my approach as “monkey style,” though I can no longer remember his rationale for his own approach.
Don’t ever eat with my mother then. She does this every. single. time. and it drives me batty. She cuts up the entire plate of spaghetti into 1/4-inch pieces. I once called her on it, and she said it was easier to eat that way. What, are you 4 years old?
Popcorn. There’s got to be a dozen ways to eat it, but only one correct way: picking up one or two pieces at a time with the fingertips and plopping them delicately in the mouth.
NOT grabbing a handful in your hand and then picking each piece up with your tongue like a bloody anteater.
NOT grabbing a handful, holding it beneath your chin and snarfing at it with your face like a hog in a trough.
NOT grabbing a handful and pouring all the pieces into your mouth with your head titled back like you’re filling a corn hopper.
NOT throwing each piece into the air, tilting your head back and catching it, yelling “two points!” after each succesful catch.
NOT, Og forbid, throwing it across the room into your brother’s open mouth, and jumping up in glee and hooting when you lodge a piece in his right nostril.
I have spoken.
Ain’t parenting grand?
I put Parmesan cheese on my popcorn. It says I can do that, right on the side of the canister.
So there.
What about holding the bowl under your chin and snarfing at it with your face like a hog in a trough? My kids do that and it drives me batty.
I hate popcorn, JFTR. I think it smells awful, and tastes even worse. They do that do make me nuts.
Damn kids.
I really don’t understand people’s aversion to ketchup. I really only eat it on fries and burgers, but I make a big deal out of the fact that I am having ketchup. I pour a great big blob of it on my plate, cut up my food (and don’t even start that you aren’t supposed to cut a burger or fries and eat them with a fork…that is the way I do it and it is fantastic) and each bite is then dipped into ketchup and/or mustard. If someone at Bennigans has a problem with the way I eat my food they should probably go to another resturaunt, or watch out of the corner of their eye and quietly mock me to their dining companions.
Genius! Pure, unadulaterated genius. Unfortunately, he won’t get it.
Why this aversion to letting those of us who are less coordinated do things that makes food easier for us to eat? (I’m not singling you out, Scarlett67, I’ve seen this a lot) Would you really rather watch us get whatever it is on our faces, shirts, and possibly socks (this has happened to me)?
You’re supposed to eat sushi with your hands - not chopsticks (those are used for sashimi tho). Hold the sides of the piece with your thumb on one side and your middle finger on the other. Use your index finger to hold the fish (egg, whatever) in place and invert the whole thing into your soysauce. Then eat it.
I learned this from my sister-in-law who is Japanese. LHD may very well believe that people in Japan are horking their sushi anyway they can, but the impression that I’ve got from my SIL is that this is not the case.
Further, she’s suggested that soaking the rice is insulting to the sushi chef, so if you must do it, don’t do it while sitting at the bar.
That being said, in North America most people won’t know the difference anyway, and will probably assume you’re an uncooth slob if you eat it with your hands anyway. (They will, of course, be wrong.)
I didn’t think I did. But, gosh, darn it, I realize I do have some very strong food biases.
GRITS: at the most you can add a little salt, little pepper, little butter, little cheddar, maybe a dash of hot sauce. DO NOT USE: Cream cheese, grape jelly, syrup, ketchup or lox. Gah. What is wrong with you people? YEAH, YOU PEOPLE. Transplanted Northerners.
FISH ON THE BONE: F’crissake, you drag the fish meat off from the bone using a fork with slow dragging motion. You don’t hack at the fish across the bones, with a knife. You wanna mouthful of bones to choke on?
IN-SHELL SHRIMP: Oh, for god’s sake you don’t eat the SHELL…
SPAGHETTI: Do whatever you want on your plate, but I’d really rather you didn’t chop up the whole freaking pot of spaghetti noodles when you’re serving me, or swish the sauce around the dish until it resembles something from a can of Chef Boy-ar-dee. Meat sauce is a cheap way to get out of making meatballs.
WATERMELON: Oh, spit out the seeds already. It’s grosser to pick them out of mouth with your fingers. Believe me, as your viewing audience, I’m telling you true.
FRIED CHICKEN: I don’t care which head of state I’m dining with: fried chicken is finger food. I refuse to eat this with a knife and fork.
Oh yum! I’m with you. I also like using Jane’s Krazy Salt. Hmmm…I think a late night snack is in order…
I don’t eat ketchup on my fries, but I will dip my potato chips in it. Other than that, ketchup is used mostly on burgers and hot dogs, and sometimes in various recipes.
The way I’m visualizing this, I’d probably end up with my index finger in the soy sauce.
What about salt cod, or do I have to call it polenta to do that? 
I had baccala with polenta in Venice, and it was great.
I’m sorry, but that’s just wrong. Meat sauce is far superior to meatballs for spaghetti. With meat sauce, you get meat, sauce, and pasta in every bite. With meatballs, you don’t, unless you cut up the meatballs into little tiny pieces, at which point you might as well be eating spaghetti with meat sauce. Meatballs are better in soups or sub sandwiches, or by themselves.
OK, speaking solely about my mother: She knits, crochets, and does a multitude of other handicrafts and has no physical disability that precludes her from smoothly handling a knife and fork. There’s no reason why she can’t eat spaghetti properly, like the rest of us adults, without resorting to hacking it all to bits the second the plate is put in front of her. There’s a way to get it to her mouth without getting it on her clothes: roll it up on her fork. Easy! Just do it slowly and carefully if the prospect is so frightening. Why must she regress to eating like a child?
*Mind, this is not the only wacky habit my mother has . . . it’s just the one that’s germane to this thread.
Other people’s habits don’t bother me, but when I’m cooking and eating a whole pizza at home, without company, I’ll pick the whole thing up and take bites from the crust first, all the way around until it’s gone, then continue eating the pizza in the same way. This is partly because I’m too lazy to slice it, and partly because I’m not good at eating really hot food and this method gets every mouthful at the perfect temperature. My housemates think it odd, though. Come to think of it, I use the same method when eating pizza with a knife and fork in a restaurant.
I have a slightly more refined way of eating popcorn - bring the bowl gently to your chin, extend your (moist) tongue in a delicate manner & elegantly stick it in the popcorn. It’s perfect!
(disclaimer - I really only do this at home, and only when no one else is sharing that particular bowl of popcorn with me)
What bugs me, though I don’t think I’ve ever actually voiced my irk (I hope!), is when people use a big spoon as a foil for twirling long pasta onto their forks.
You want to make meat sauce and big-ass meatballs? Great. Terrfifc. i approve. You wanna be all skimpy and be all cheap and just make meat sauce? I cry foul.