30 Day SF & Fantasy Challenge Day 20: The Best Movie To Get High With

One of the stories that my father always told me growing up that amuses the hell out of me is that of going to see 2001: A Space Odyssey in theaters when it was released. After serving in Greenland building radar installations during the sixties for the air force, he came home and one of the first things he saw was that. And while the movie blew him away, being a long-time science fiction fan, it was the experience of seeing so many people in the various showings getting high while watching it that was almost as fascinating and wondering what kind of experience they had with that. So today, we want to know what the best movies to watch while high for either SF or fantasy and, if you did so, what was it like?

Bonus Question: Which film would be the worst one to try and do this with and why?