1. In my 20's:
    I hope I meet someone or run into friends!
  2. In my 30's:
    If you aren't the bartender, then not only should you not speak to me, you shouldn't even be here. Leave me alone and leave my friend the barkeep alone, too. We were having a conversation, you jerk.
  3. BONUS:
    The exception to my attitude in my 30's is if you buy me a drink and just want to say hi for a second, like the kind stranger in this bar just did.