Arsenic and Old Lace.
Looking at the cover image, along with seeing the name Frank Capra (of It's a Wonderful Life or Mr. Smith Goes to Washington fame), might give the false impression that this is a light-hearted screwball comedy. In reality, it's anything but.
Here's the blurb:
A drama critic learns on his wedding day that his beloved maiden aunts are homicidal maniacs, and that insanity runs in his family.
No, really. That's what this film is about. It's deliciously awful. Cary Grant's facial expressions are priceless. And the characters in this wacky film are mood lifters, despite the creepy premise of the film.
C'mon, you know you wanna watch it.