Video: THE EXORCIST - Trailer - HQ - (1973)
A teenage girl, horrifically disfigured, sits up in bed and projectile-vomits dollops of thick, green gloop onto the face of a priest. Then, in a stream of appalling profanity, the girl confirms what we already guessed: that she happens to be possessed by the Devil. As plot twists go, it's not exactly clever or sophisticated. But the scene is nonetheless hugely effective: this is, after all, one of the climactic moments of The Exorcist, which in turn is among the most terrifying and brilliantly-executed horror movies.