Play Dead

You lie Prone and pretend to be an ordinary skeleton. As long as you don't move or take any actions requiring anything other than your mind, you appear dead. To see through your ruse, another creature must succeed at a check against your Deception DC, either by Seeking or Recalling Knowledge (typically using Religion or an appropriate Lore skill). This ability doesn't work against creatures that already know you're an animate undead unless you have changed your appearance.