I'm going to add a couple of my big annoyances. Virtually every native English speaker uses various contractions when speaking, but some people don't seem to know what some of them mean. Things like "would have" get shortened to "would've." BUT--and I hate this--I have seen IN PRINT, instead of using "would've," people will write "would of," which is not only incorrect, it also makes no sense.
Another thing I strongly dislike is when people mindlessly use filler words such as "you know." An occasional use is fine, but not four or five uses in two consecutive sentences. Sometimes I feel like yelling, "No, you idiot, I don't know. I'm waiting for you to tell me."