Once upon a time (that time being 1972), Hollywood icon and comedy legend Jerry Lewis thought it would for some reason be a good idea to make a movie about the Holocaust in which he played a clown who led children into the gas chamber.
Because what could go wrong with that?
Apparently everything. Everything could go wrong with that.
It was called The Day the Clown Cried, and it was not good. After some disastrous test screenings, Lewis was so horrified by what he hath wrought that he put the movie in a vault, vowing to never let it see the light of day.
The film is apparently an unholy train wreck of tone-deafness. At this year's Cannes Film Festival, Lewis said of his great cinematic miscarriage, "It was bad, and it was bad because I lost the magic. You will never see it. No one will ever see it."
One of the few humans to have actually laid eyes on the movie was Spinal Tap and Simpsons star Harry Shearer. Here's his assessment from a private screening in 1979:
With most of these kinds of things, you find that the anticipation, or the concept, is better than the thing itself. But seeing this film was really awe-inspiring, in that you are rarely in the presence of a perfect object. This was a perfect object. 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. "Oh My God!" – that's all you can say.