5. Shortbus (2006)

Hedwig and the Angry Inch director John Cameron Mitchell was inspired by real-life sex parties that took place in New York in the early 2000s when he wrote this controversial film. It features a large cast of sexually adventurous characters with a wide array of preferences, which wouldn't exactly be a huge deal if the sex in the film isn't real — but it is. The unsimulated sex caused some critics to categorize it as porn, but Mitchell defended his work, saying that he has "de-eroticized the sex to see what's left over."