I think some people might hate me for this list
  1. Thanking someone for holding the door for me
    Occasionally I'll do this, but I don't think I should have to thank someone for just being a decent human being. Do you really need my verbal affirmation that I'm thankful? I didn't ask you to hold it - I could've opened it myself.
  2. Covering my mouth when yawning
    This is a natural response to having little sleep or being tired - it doesn't mean that I think you're boring. Why do I have to hide my yawns from the world?
  3. Having to say "bless you" to anyone who sneezes
    If I don't know you well enough to say "Hey!" why do I feel obligated to say "Bless you!"? It's a very odd phenomenon.