I generally say something like "you know, I'm a complete dork, but that thing where you slurp your coffee/ rub your feet like that on the floor/keep strangling our cats just drives me nuts. I know, I know, I'm the sensitive one here; can you PLEASE try not to do that around me if you can??? I know I'm an assshole" and usually I'll get a "oh, I didn't know that bothered you" or "I didn't realize it came off like that" or whatever and they'll try to stop, which will only work part way but will at least make me feel better.