1. A conversation falling into silence
    There are like four people who are the exception to this rule--my parents, my brother, and my best friend. Other than that, I hate awkward silences with a passion.
  2. Hugging everyone in a group except that one person you don't know that well.
    I can't even begin to guess the number of times I've been saying goodbye to people in a group, and I've hugged all of them, except that one person I don't actually know or have just met. I feel rude, but I also don't want to invade their personal space.
  3. Replying to "Happy Birthday" with "You too"
    Suggested by @estherlimtf