Worse than a Negative Nancy, or Debbie Downer. This person is excessively negative, even during the happiest of times. They find themselves completely incapable of being positive. Some might call them pessimists, but they are much worse. They seem to be addicted to negativity.
My hubby is the biggest negaholic EVER! I surprised him with a new flatscreen tv for his birthday. Instead of smiling and hugging me, he instead frowned and asked how much I spent on it since he was planning on buying a new hard drive for his computer with our extra dough. Then he frowned some more because he realized he was another year older.