'Nymphomaniac' is the latest film to come under the microscope, as much for its in-your-face sex scenes as for the chilling tale of a woman prevented by her desires from having any kind of ordinary life.
Director Lars von Trier has made no bones about the performances he required from his actors including Charlotte Gainsborg, Willem Defoe and Shia LaBoeuf until, when they could go no further, porn stars were recruited for the rest.
Sex scenes on celluloid have often stirred debate, with fans discussing at length whether actors had real-life sex or were faking it. Some actors have held their hands up in pride, while others deny anything other than acting.
Check out our sex - sorry, six - films below which have stirred debate and tell us which of them you think contain some real-life hanky-panky...