I’ll go first. Mine is the instant knockout drug. Like Dexter’s intramuscular injection that causes someone to immediately lose consciousness. Or in the movie Split where there’s the aerosol spray in your face that makes you instantly unconscious. Or pretty much any time someone uses chloroform.
When they provide exposition about something that lead to the current story, but the exposition is about something way more interesting than what is happening in the current movie because the current movie is just generic whatever.