What about A Bucket of Blood? The 1959 Roger Corman movie. One of my personal favs.
The synopsis: “A dimwitted, impressionable busboy at a Bohemian café is acclaimed as a brilliant sculptor when he accidentally kills his landlady's cat and covers its body in clay to hide the evidence. When he is pressured to create similar work, he becomes murderous.”
It’s really, really funny and honestly pretty dark for its era. (No onscreen animal cruelty, btw.) Great performances and mood. Plus, because it’s a Roger Corman B-film, it’s only like 66 minutes long, if that does anything for you.