The quintessential must-watch scary movie that will have you up for nights.

Linda Blair projectile-vomiting pea soup has become something of a cultural joke by now, but actually seeing "The Exorcist," you'll find it surprisingly hard to maintain a detached, ironic air. Instead, watching trapped, transformed Regan MacNeil (Blair) spider-walk down the stairs or make highly-inappropriate use of a crucifix while her terrified mother (Ellen Burstyn) looks on, you won't be laughing. You'll be crossing yourself.