“Hi, Mom!” (1970) is a dark comedy directed by Brian De Palma and stars Robert De Niro. It’s a sequel to Greetings (1968) in which De Nero reprises his role of John Rubin who is now a voyeuristic filmmaker. John later falls in with a group of militant black activists leading to the film’s most memorable scene in which he participates in an experimental theater performance. The show is called “Be Black, Baby” and requires its white audience to don blackface and be subjected to an escalating series of abuses by black actors in whiteface until John arrives as a seemingly real NYPD officer and proceeds to put the white audience members under arrest. De Palma and De Niro’s next collaboration would be 17 years later for The Untouchables.