i am a genius

SCENE: The C***y-McG*** household. The incumbents are seated on the sofa watching Thirty Days Of Night, a film in which vampires terrorize a small town above the Arctic Circle where the sun doesn't rise for a month in Winter. The film is about half-way through.

ME (*lightbulb moment*): The vampires have come to the town because it's so dark, haven't they?
B: *sigh*

Ah, my mighty brain.