1.When someone adds something not funny at all to a funny joke makes you sad in the process.
2. A person who constantly makes everything funny really stupid and unfunny and also makes negative comments on everything positive.
1. Person 1: Dude, the Browns are so beast they are totally gonna win the superbowl.
Person 2: BEAST LIKE YOUR MOM LAST NIGHT!
Person 1: Buzzkill, no wait that made me sad you thought that was funny, buzzkilljoy.
2. Person 1: Man, that guy is such a buzzkill, i made the funniest joke in science but he turned it gay.
Person 2: Well he was a killjoy to me. I was asking some people if they wanted to go the the football game on Friday. Now, thanks to him, i know its going to rain and the game might get cancelled.
Person 1: I guess he's a buzzkilljoy then.
Buzzkilljoy: Hey guys, it said on facebook you ignored my friend request. Hehe must be some mistake.