Hey, seawhale. Have you considered that this guy might be mentally ill? (Perhaps borderline?) I am just guessing. But you might check into the book "Stop Walking on Eggshells" to see if any of that sounds familiar, and if so, what you can do about it.

I suggest just trying to ignore the guy. It sounds like he can't be a good friend, and you don't need him on FB. If he puts a cup on your desk, then just throw it away, etc. And keep thinking about the positive aspects of your job.