You assume too much

I have a problem with people who assume a degree of familiarity that is not present between two people. I'm not talking about people who are over friendly, but people who do little weird things that kind of cross the line. Example: While at work day before yesterday one of my coworkers, let's call him Physicist, comes up behind me while I am very busy and begins DRUMMING ON MY HEAD! Not lightly either, but actually quite hard. I have no idea what he was trying to accomplish. Who does this? What is the point? Doesn't this seem like something a four-year-old would do? What he acheived was giving me a headache and pissing me off. I don't know Physicist that well, we haven't been working together that long. Physicist also tends to be more hands on than I like my work acquantances to be.

On a positive note, my roommate has returned from his trip to Canada (or Canadia if you prefer), so hopefully the new apartment will be getting sorted in the next couple days.