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