Ever have one of those moments were you did something innocent/harmless and that made someone mad at you?
Here is my list
When I was about 10 years old in English class the teacher wrote a sentence on the board and I asked if it should have an exclamation point at the end. She absolutely flipped out at me. I felt embarrassed and humiliated in front of the whole class. Never quite got over it.
First time I’ve articulated that in any form to anyone. Feels good to get it off my chest.
Speaking English. English is outlawed in my school, so the teacher reprimands us when we speak it. And our course isn’t even a French-learning course…
I had a home-ec teacher completely lose it when I used a liquid measuring cup to measure a solid ingredient.
In my defense, I grew up in a poorer family that didn’t fuss with such details. Heck, we probably only had one set of measuring cups, never mind separate ones for liquid and solid!
But that teacher went nuts! In front of the whole class. I think she made me cry. 
what a jerkwad 
I’ve lost track.
Crossing my legs on the subway.
My brother was living in a house with no heat, 3 working electrical outlets, was sleeping in the kitchen with a 35,000btu propane heater about 4 feet away from him as to be warm during the Knoxville winter. (Earlier (and now, I hear) he was living in a single room in a mobile home, so this house was a step up.)
He is also the beneficiary of an inheritance trust valued, at the time, at ~ $1 million. My uncle was the trustee. There is to be no distribution of assets from the Trust as my brother was considered not competent enough to manage the money - i.e., the money will remain in Trust as long as he lives. And he isn’t competent to manage the money - my brother has what is best/easiest described as a case of arrested development - he views the world as a 14 year old would, though he’s in his late 40s. It was specifically stated in the Trust that it was to assist Brother with his “health and maintenance”, and a house with no heat and a huge fire hazard 5 feet from his head struck me as meeting this clause rather nicely.
Thinking there was something morally wrong with this (the house he was living in was owned by my parents and they were in no hurry to fix it) I worked with him for a month to look for a house that would meet his requirements: relatively new (less than 20 years old) with a large fenced-in lot for his dogs. In the Knoxville area, such a house could be had from $80k on up. The idea, of course, was that the Trust would be able to buy the house, essentially being an exchange of assets: sell some Trust assets to raise the cash, make an all-cash offer (which means we could have knocked an easy 5-15% off the sales price), and purchase the house.*) In addition, the Trust would have been responsible for home repairs, maintenance, etc - there were plenty of handymen in the Knoxville area who would have loved to have been on retainer (for want of a better word) for those problems my brother could not have handled.
I have no desire to get into it, but let’s just say that this idea went over extremely poorly with my uncle, so poorly that I’m still dealing the repercussions today (my brother refuses to speak with me, as does my uncle) a full six years after this effort. I did not help in this, once losing my temper with my uncle and having a screaming fight with him (Uncle actually came to Knoxville, but get this: refused to visit Brother’s home to see if it was an acceptable living situation. That’s what set me off, and I have since apologized, but to no avail.)
Had I let the guy burn to death, things would have gone better for me. WTF!?
*It would have been a little more complicated than this as we did not want any potential liability in re: to owning the house to possibly impact the Trust assets, but we didn’t get far enough into the process for this to even be discussed.
I poured out a bucket of cold, dirty mop water once. Apparently my wife was saving it for later.
I posted a diatribe on facebook about how I would kill myself if I saw ONE MORE PICTURE OF SOMEONE’S KID. Apparently I did this mere seconds after one of my friends had uploaded 400 pictures of her new baby. Of course she thought I was talking about her.
When I was 17 I lived with my then-boyfriend. One night while he was out I cleaned the apartment and emptied the ashtrays. He FREAKED OUT on me because apparently said ashtrays contained roaches that he & his loser buddies wanted to smoke later.
I let out a yelp and cursed in pain when my wife accidentally poked me in the eye while making a gesture.
My outburst upset her so much that she began to cry. She didn’t calm down until I apologized.
So basically, I had to ask her to forgive me for her poking me in the eye.
harmless things that people made people mad at you
If you’re asking married people, you’re going to need a bigger thread. 
In the Navy, while I was qualifying in the steam plant, I desperately needed a signature from one fellow, so I was doing what everyone did in those circumstances: whatever he asked me to do. He sent me back to the workshop to fetch his coffee cup and fill it with joe.
Before filling it, I scrubbed the cup clean, removing a quarter inch of fur that was growing in the bottom. It was nasty.
He chewed me out good for that, telling me he had worked six months growing that fur. He was serious about it, and I don’t think I got the signature.
Me to future psyco-ex, on entering a Wal-mart: “I’m gonna get a soda out of this machine. Do you want one?”
Future psycho-ex: “No, I’ll just have a sip of yours.”
Me: “Here, wanna sip?”
Her: “O.K. (sips)- Yuck! Why’d you get root beer? I hate root beer! How could you do that?”
Asking my BIL what preppers are prepping for. I really wanted to know, still do.
Oh, yes, I once scrubbed out a teapot. I can still feel my friends grit teethed explanation as to why I should not.
You meant to post in the “Harmless things that people did that made you mad at them,” right? Because, y’know, you can choose to hide certain posts, and that’s on you, not on them.
You wanna make it a giant thread, ask parents.
Toddler: I need cheese for lunch!
Me: You mean, Daddy, may I please have cheese for lunch?
Toddler: Daddy, may I please have cheese for lunch?
Me: Sure thing! [slices some cheese]
Toddler: [collapses on floor sobbing for several minutes before she can speak] I WANTED GRATED CHEESE!
LHoD, you have that right. Mine has lost it over getting the wrong cheese, someone sitting on the couch, someone reaching the bottom of the stairs before he does. The worst is when your transgression is irreversible, like putting the wrong sauce on his pasta, or mixing in the wrong vegetable with his rice.
A guy once threw an ashtray at me in a bar, and then cornered me in the bathroom wanting to fight because I looked at him for what he thought was an unreasonable amount of time.
I was just people watching and my eyes stopped at his table for 4 or 5 seconds. What a nutbar.