Wow, I'm behind the times. (An expression I probably wouldn't have liked if I'd learned it anywhere else, but love it because of its associations.)
My number one peeve, and really this is not an expression issue, but an etiquette issue, is what has already been discussed - someone asking any form of "How are you?" but not stopping for an answer. I do have a fondness (probably also associational) for "how ya doon?" but only if the answer is listened to. Of course the responder owes a brief initial reply, but hopefully (a word I don't mind) that can develop into a conversation with real depth. The main thing my friends and I talk about is prolly how we're doon.
Some expressions that rub me the wrong way:
"personal friend" - what other kind is there?
"non-starter" - what does that mean?
anything with literally violent imagery, that someone uses casually, like "I could kill you for that," "slap you upside the head," and especially, "just shoot me now"
Chrissi, good news, I don't think I've ever actually heard anyone I know use the word "trash" to describe actual humans. I agree, it's shocking.