I could write a novel on how many things get on my nerves. Seriously. The world is such an irritating place to me.
This is because a lot of the time, people are just so baffling and illogical. At least to me. They do these things that there isn't any reason to do, things that are actively detrimental, and can't be bothered to change or consider others because that's the way they've always done it. The stubbornness of people, their refusal to be considerate of others and opposing opinions... I think that is the biggest thing that grates on my nerves. The imperfections of humanity are so frustrating, and they frustrate me to no end when my feelings force me to display them as well at times.
Arguments fit into this as well. They have no productive purpose, as most people won't change their mind. I find the only reason people engage in them is so they can yell over whoever happened to oppose their precious opinion, not to do anything of value. Arguments on the internet exemplify this most intensely. Yelling at people in incoherent English is some kind of expected norm on certain sites (like Youtube comments) and I find it just... such a sad example of how human brains still haven't fully evolved past primitive instincts and drives. (Of course, not to say that humanity is all bad, but... there really is so much negative, it's difficult not to think about it. Especially when it is constantly thrust in your face.)
Speaking of the internet, one of my bigger pet peeves is incoherent English. Particularly people who refuse to capitalize anything in their sentences, use chatspeak, and spell everything wrong. If you live in an English speaking country, what went wrong in your English class? Was it somehow ridiculously inferior to mine? And then there's those who I know know better, but still do this anyway because "it's the internet lawlz." That attitude gets on my nerves intensely and I find it even more irritating. People just pretending they don't care and don't take anything seriously in some immature attempt to be cool.
Also, bad formatting of written posts. Anywhere on the internet. My brain can't handle even the slightest bit of formatting off. Whether it be a slightly too bright font color, a long post with no paragraphs, or an overly fancy cursive font. Aesthetic choices affect me deeply, and make it really difficult for me to read the surrounding text. It becomes this struggle, and most of the time, my brain just filters it out and doesn't even perceive it as existing. I just wish people didn't feel the need to make things so fancy and unnecessarily flashy. All I want to do is read, I'm not here to be assaulted by your bad sense of design or grammar.
I could go on, but I feel I've ranted enough. Just know that sometimes, the world makes me want to punch everything. These little things are insignificant on their own, but they really add up and make it hard to not just scream at someone sometimes.