someone who brings a joke down and who ruins the moment
also can be reffered to as a debbie downer in some situations.
Sometimes someone acting in a douche baggy manner
Spencer is such a suck, he's a fun ruin-er
I wish Spencer would stop being such a suck
Really? You had to delete that post. You're such a suck it was funny!
You don't want to come help me clean up because you're tired? Urg you're such a suck!