Zero Hit Points

I had a dream night before last that I went on a killing spree. It was scary, because everyone was trying to kill ME at first. I remember walking in the woods near my workplace, and 2 guys in suit and tie started trying to beat me with their briefcases. I don't remember how I killed them, but when I did, I threw a little white card on their chests that had a big zero on it. Under the zero, in smaller letters, were the words, "HIT POINTS."