Buster
Definition 1 of 5
Pro Tip 1/2
Negative Connotation
Used to describe someone ruining fun, often disliked for this reason. Don't invite him; he's a total party buster.
Pro Tip 2/2
End of Activity
Implies the activity ended because of the 'buster's' intervention. She's a game buster. When she loses, the game is over.