Note that you very much can get "floating pink elephants", but not from psychedelics — you need to get into deliriants for that: Datura plant in small doses, red mushrooms, diphenhydramine or amantadine in large doses, and some other stuff (like these tablets from military first-aid kits: https://pubchem.ncbi.nlm.nih.gov/compound/Aprofene).
These things were somewhat popular in my language segment of the internet about ten years ago. A lot of people were experimenting with the stuff. Usually one trip was more than enough to never want to repeat that again.
Try reading some trip reports on erowid if you're curious.