Movies
You're a creature of the night, Michael. My own brother, a goddam shit-sucking vampire. You wait 'til Mom finds out!
— Sam · The Lost Boys

Behind the line May contain spoilers.
Our reading
An editorial interpretation.
An exasperated sibling calls his brother a vampire, then threatens to tell Mom. The reaction mixes supernatural horror with familiar family outrage: even being a creature of the night apparently doesn't put Michael beyond parental authority. That sudden drop in scale supplies the joke.
Context reviewed