Betsey Brown Is director Peter Vack's sister. He convinced her to perform fully nude (for the first time in her career) and in graphic sex scenes, including pretending to lick a man's butthole while he licks hers. Their parents also appear in the film and watched those scenes at the premiere with a large audience.
Peter Vack said it was very difficult finding investors when his pitch was that the film was about two people who share an anal fetish and he wanted his own sister to play the lead.
When someone called the film a "shock comedy," Peter Vack said he'd never heard that term before. He thought he was just making a snobby arthouse movie.
Peter Vack said he originally wrote the sibling characters played by him and his real life sister Betsey Brown to be lovers. But as he was writing the graphic bathroom sex scene in the first act and imagined being totally naked with his sister having sex, he realized he hated that idea. So he set the script aside and came back to it later. At that point he dropped the incest idea and rewrote it.
Media site IndieWire critic David Ehrlich called this "one of the most disgusting movies ever made."