Deathie is a term used on people who always seem to have something that is better than you. When you get something new, the deathie always bought a similar thing half a year earlier, which still is way better than what you recently bought.
You: "Hey deathie, I got my new HDD today."
Deathie: "I've have a 400GB HDD in my other PC. But I bought that 3 months ago"