If you want trippy animated films look up any old films by Ralph Bakshi. I still have most of his collection on VHS. Trippy stuff from the 60s and 70s. Fritz, Wizards and Coonskin are classics that you should see for sure.
Dead Leaves probably shouldn't be watched sober. It's nonstop craziness.
The original Heavy Metal film is a good choice as well.
Then there's Wicked City and Akira if you're into Anime. Even if you're not they're worth a watch.