The phrase references a type of social activity centered around viewing the third installment in the Harry Potter film series. Participants consume alcoholic beverages or other drinks when specific events, character actions, or dialogue occur during the movie’s runtime. For instance, individuals might drink whenever Sirius Black appears on screen or when a spell is cast.
These types of activities foster social interaction and can enhance engagement with the chosen film. The element of chance and the communal experience of shared rules add an extra layer of entertainment. While the concept is relatively modern, it builds upon the long-standing tradition of social gatherings centered around shared media experiences.