I don't get irritated by the trivial things other people do, but I'm bothered by my own sloppy speech.
I say "gonna" hafta wanna s'posed'ta coulda
I contract "I will not" to something like "um'not" and instead of just contracting "we are ready" to "we're ready" I will also contract "boxes're ready" "wheels're ready" and so on.
I say "goin'" lookin'
I run words together like "can we" as "canwee"
I use the word "got" instead of some form of to have.
I'm sure there are many other habits of speech that I would change if I were more mindful of them.