The two most intense hallucinations I ever had were on Gelcaps called Vanillas (30% MDA, 30% MDMA, 30% Meth) about 8 years ago.
The first time I railed one at my friends house, I was sitting on a bar stool.
I did the line, looked up immediately and my friends short spiky hair turned Medusa like, with undulating tentacles flowing 3 feet from his head.
Then I fell off the stool.
Another time I did one of these at an outdoor rave at a campground. I was walking a dark path towards the main stage with some friends and we we walked by a large two story brick building covered in graffiti, and there were cars parked out front of it, beside the parking meters.
I commented that it was strange people would park at the meters when the rest of the campground had free parking.
Turns out neither the building, cars nor parking meters were actually there.