1. Back of knee.
    This is THEE worst.
  2. Top of foot.
    Good luck with that one.
  3. Knuckles.
    Pfff, kill yourself.
  4. Elbows.
    You gotta be fucking kidding me.
  5. Ankle.
    Karma's a bitch.
  6. Wrist bone.
    The ankle of the hand. Day ruiner.
  7. Neck. Just below your ear lobe.
    Is this real life?
  8. Right on that lil bit of webbing between fingers.
    Suggested by @eliyudin