Voldemort
Realism at it's best.
I once left due to content, which made me physically sick within the cinema. I saw, 28 weeks later, the part where the woman gets her eyeballs pushed out made me throw up. It was gross. Too gross.
But I once witnessed someone leaving a cinema quite fast. It was Sin City, and this middle aged man practically ran out of the room when the first nudity scene came.
(ps: Daisy-Boo, why have you got a picture of my cat as your avatar?)
I only remember leaving half way through four weddings and a funeral. It it just didn't get me like other people.