The 1972 movie "The Day the Clown Cried" — starring Jerry Lewis as a failed circus clown who is employed to entertain and lead children into a concentration camp gas chamber during the Holocaust — has never seen the light of day.
It has generally been considered possibly too offensive.
Speaking at the Cannes Film Festival in May, where he had a film showing for the first time in more than 20 years, Lewis told reporters: "No one will ever see it, because I'm embarrassed."
"I believed in the work and the way it should have been, and it wasn't," said Lewis at the time.
"The Simpsons" and "Spinal Tap" star Harry Shearer saw a private screening in 1979 and told Spy Magazine: "This movie is so drastically wrong, its pathos and its comedy are so wildly misplaced, that you could not, in your fantasy of what it might be like, improve on what it really is."
The footage has been buried in a vault for the last 40 years. But some rare behind-the-scenes footage has leaked. And it's worth a watch.
Here's the clip: