Here's my pet peeve: people who have pet peeves.

My biggest objection is to people who think they way they happen to say something is better than that of the speaker of some other dialect or regional variety of whatever language they speak.

I say "waiting for" someone not "waiting on" someone (unless in the context of a server in a restaurant.) When I moved to Ohio once upon a time I noticed that people there said "wait on." It did bug me at first, but then when I went other places, I noticed that people there used it too. I even heard it back in California, where I am from. I never heard it growing up, but now it seems like it's taken over most places.

Speaking of "over". My students will ask me what the paper is "over." It's not "over" anything, in my dialect; it may be on or about something, but never "over." (A test can be over something, but not a paper.) Yet ultimately what can you do? It's not one student who says this, but almost every single student, so I have to accept that as just something people say. My earlier hypthesis was that the students were mis-applying the concept of a test to the context of a paper. A test can encompass a certain amount of material, but an essay does not. Now I think it's just a preposition. Who cares what preposition someone uses?