look up any word, like the eiffel tower:
it is the person who puts everyone in a bad mood by saying something depressing in the middle of a joyous occasion.
Person 1: "Man this is a great party!"
Person 2: "I agree! I'm having so much fun!"
Person 3: "You know, we could all die later."
Person 1: "Gosh Person 3, why are you such a cake pooper?"
by Tenley May 22, 2007