Or, things that just never occurred to you to have an opinion about.
I left off things like, ketchup on a hot dog, yea or nay because every right thinking person knows that it’s wrong but they do hold an opinion. 
What are yours?
Toilet paper: it depends on how the paper holder is constructed.
Ketchup on hot dogs: a must. How can you ever eat them without, and why would it be an issue?
Shoes in the house. Never realised it could raise such passions.
I learned this one from an ex. I’d get “the look” if my shoes stayed on past the front entryway. She had also decided that bare feet/socks also were evil for walking; slip out of shoes into flip-flops for in-house walking. Slip out of the flip-flops for lounging on the couch or bed, but you had to slip your feet back in before standing up. The flip-flops could NOT leave the house. When I had a foot injury that required a cast, she freaked out… I had to sleep with my foot off the bed, lest my cast somehow contaminate things.
She also had very strong opinions of how I was to hold my arm when holding her hand-- I had to have my arm out straight and pointed straight down, rather than bent, which she felt was effeminate. Despite the fact that we were nearly the same height, and my arm had to bend to accommodate her hand.
I think I get why she’s your ex.
No kidding. That’s crazy talk.
How to fold towels. Apparently not folding them into thirds is a sin against God and Man.
Cupboard doors must be closed.
Toilet tissue under so the weight of the roll will hold it while you tear it off. Otherwise, you get 3 yards when you pull on it.
Lights not in use shut off.
Canned goods right side up.
U.S. currency bills all facing the same way.
I know… I’m neurotic
Was she Asian?
But you do have opinions on those things. I was thinking of things that you hadn’t previously even thought to have an opinion on.
I have been at a Swedish/Japanese household with a distinct line on the floor in the hall and a notice stating “No shoes on the other side of this line”. On the wall hung a samurai sword indicating what would happen if you didn’t obey.
Saying “No problem” instead of “You’re welcome” in response to “Thank you.” I don’t care what anyone says to me when I thank them but some people get ridiculously up in arms about “No problem.” You know, stuff like, “OF COURSE IT SHOULDN’T BE IMPLIED THAT IT COULD EVER BE A PROBLEM TO SERVE ME! IT’S A JOY TO DO THINGS FOR ME! GAH!”
Just about everything people fight about at the office. I really don’t understand why anyone notices someone else’s coffee cup being int he sink or on the counter.
Honestly, it makes me think what a wonderful life that would be, where something so small actually rated my attention. Maybe they’d like to take on some of my worries for a day. . .
I can’t believe that people have an opinion on:
Which elbow you sneeze into (seriously - I was once told that I should only sneeze into my left).
Whether you should grip the door with a paper towel or your hand after you wash your hands.
Whether or not I wash the potatoes before I peel them (if I boil them after, does it really make a difference, especially if I’m removing all the skin that would contain the dirt?) and whether I use special vegetable cleanser.
Whether it’s ok for babies to use a pacifier (seriously - who gives a crap?).
Where babies sleep - parents’ bed or their own (as long as they’re safe, it’s no one else’s business).
Ordering milk in a bar!
You can order milk in a bar? Like without booze in it?
Referring to a group that includes women as “you guys.” Although I guess this is really an example of things I can’t believe people get incensed about.
Which reminds me: Using a preposition at the end of a sentence.
Some cocktails call for milk. A fully stocked bar should have it. Whether you order it is another story; the bartender might not know how much to charge and have to decide what glass to serve it in, but there should be both milk and cream.
Sure. I order virgin white russians all the time.
A recent one I learned was putting pickles on a chicken sandwich.
Huh!
Well, I’m the guy at the bar who orders whiskey on the rocks “with some booze in it this time!”
…which i personally find delectable 