All of them. At some point, every word and phrase has annoyed me. As for ones that annoy me consistantly, "I'm not being funny" said just before a serious statement. "Calm down" no matter what, the phrase "calm down" will only increase my anger, even if I wasn't angry in the first place. "Modern music is bad" and other variations of it, because it's simply a matter of taste. It annoys me even more when I hear teenagers saying that they hate modern music and only like music from before they were born. It just sounds too much like they're trying to be original, which is another thing that annoys me, but I won't go into that.
When YOLO and swag were used seriously, I used to dislike them, but since it's become common for them to be disliked, I will admit to using them. I use YOLO a lot as a reason for things just because I'm awful at explaining things and it's funnier than "just because", and I use swag to describe myself because I'm that much of a narcissist. But back to phrases I don't like, "is it just me" because more often than not, no, it's not just you. Also, most Welsh words and phrases annoy me and I've had to put up with them all my life. Especially "cwtch" which if you don't know, means hug or cuddle. "Nerd","Geek" or "Dork" used by people who are clearly not. My rule is, if they have any of those three words printed on a t-shirt or jacket, they are not that.