Here is my list, depending on the mood:
Stoner Comedy Classics:
- Up in Smoke (Cheech & Chong)
- Half Baked
- How High
- Harold & Kumar
Stoner Classics:
- Dazed and Confused
- Fear and Loathing in Las Vegas
- The Big Lebowski
- Human Traffic
- (2001 - A Space Odyssey)
Absurd Comedies:
- Airplane
- Napoleon Dynamite
- Hod Rod
- Tenacious D in The Pick of Destiny
- Anything by Monty Python for example Life of Brian
- Barb and Star go to Vista Del Mar
Visually Trippy Movies:
- Beach Bum
- A Scanner Darly
- Waking Life
- Glossary of Broken Dreams
Trippy & Weird Movies:
- Sorry to Bother You
- Sans Soleil
- The Holy Mountain
- Bakara
Drug Movies (trippy but not recommended if you are looking for a good time):
- Enter the Void
- Requiem for a Dream
- Trainspotting
- Spun (this one at least is still a comedy)
Edit: Bonus mention Dark Side of The Rainbow, that is Pink Floyd's Dark Side of the Moon synced to The Wizard of Oz
We got that one in Germany as well