20. The Exorcist

(William Friedkin, 1973)

Possession, puberty and pea-soup as teenager Regan MacNeil feels the devil inside her.

Danger, danger! Storm-outs and faintings were common at screenings of Friedkin's psych-horror, with one theatre manager complaining, “My janitors are going bananas wiping up the vomit!”

More extreme cases included a man in San Francisco who attacked the screen in an attempt to kill the demon and another who sued Warner Bros after he passed out and broke his jaw.

Much of the trouble was apparently caused by the subliminal insert shots of 'Captain Howdy' – Linda Blair double Eileen Dietz in demon make-up.

19. Super Size Me

(Morgan Spurlock, 2004)

Playwright embarks on a cross-country Mc-trek to highlight the health risks of fast food.

Danger, danger! Impartial or not, Spurlock's queasy quest certainly made an impact.

Its claims that aggressive advertising and high-fat foods made McDonald's responsible for rising levels of child obesity stirred up a storm of negative publicity which (arguably) influenced the greed-feeding giant to scrap its 'supersize' meal option and introduce a new range of healthier choices (wraps, salads and bits of fruit).

18. Taxi Driver

(Martin Scorsese, 1976)

Lonely 'Nam vet Travis Bickle slips into a violent existential depression.

Danger, danger! When Jodie Foster-obsessed loner John Hinckley Jr attempted to off President Reagan in 1981, he described his actions as “the greatest love offering in the history of the world.”

The gunman had seen Taxi Driver – in which Robert De Niro's vigilante vet plans to assassinate a high-profile politico – 15 times and all but acknowledged the film's influence when he told Newsweek “the line dividing life and art can be invisible.”

He was more right than he knew – Paul Schrader's script was inspired by another real-life loner-turned-gunman, Arthur Bremer, who shot – and paralysed – Presidential candidate George Wallace in 1972.

Next: Triumph Of The Will, Child's Play 3, A Fish Called Wanda...