Are you obnoxious?
Here's a quiz to help you decide.
But, just in case you're still not clear, if I'm sitting at my desk with my office door nearly closed while obviously eating my lunch and reading my various news and celebrity gossip sites and you invite yourself in, sit down, and start talking to me about something I couldn't give a shit about in your personal life, you just may be obnoxious. K?
If I wanted to be social at lunch time, I wouldn't hide in my office.