According to the Urban Dictionary (yes, they are just as reliable and prestigious as Webster’s or the Oxford English Dictionary), a buzzkill is “something that spoils or ruins an otherwise enjoyable event”, “someone who personifies a big black hole where all fun goes to die”, or in verb form it means “to selectively and deliberately bring down someone’s mood by actions that are designed to irritate, annoy or downright upset a person”. Also known as a killjoy, debbie downer, party pooper, spoilsport, negative nancy, or fun sucker, they show up to the function and ruin it for the rest of us.
He will show up an hour and a half late and have to announce his entrance to everyone present. He is unnecessarily loud and thinks that his jokes will be funnier the louder he tells them and the more he (alone) laughs. He gets drunk surprisingly quickly and subsequently stumble into other people causing them to spill their drinks. Depending on how late it is, he may even fall down trying to dance breaking furniture or barware in the process. Everyone is making plans to meet up later at a bar; however, he decides to declare that the bar is so last week and anyone who goes there is a tool. Regardless, he will spill drinks, throw food on the floor, and otherwise trash the bathroom before calling it a night. And by calling it a night, we mean he passes out during the party on the couch or in cuddling the toilet in the bathroom floor.