The term defining the event where a man and a woman are having intercourse in a bedroom, and upon the time of finishing, a third party who has been hiding in the closet, unbeknowsnt to the man or woman, jumps out and yells "TEN POINTS FOR GRYFFINDOR!!!" and promptly runs out of the room. Usually works best with random hook ups, but also is well suited for sex within a relationship.
"Yo dude, you remember how Chris was with that random girl last night? I so ten points for gryffindored them"