Or, as an alternative title, "Top Five Films Darkening Humor Should Avoid".
You can put on your list your favorite films that are difficult to understand or the five films most baffling.
Favorite Inscrutable Films:
1. The Double Life of Veronique
2. Upstream Color
3. Barton Fink
4. Mulholland Dr.
5. Synecdoche, NY
Most Inscrutable Films, from my perspective:
1. Last Year at Marienbad
2. Anything by Stan Brakhage, but, let's say, Dog Star Man
Honorable mention for both lists: Syndromes of a Century