My friend said that painful would be going down a water-slide, lined with razor blades, and landing in a thick mixture of vinegar, salt, and Vegemite (aussie).
Torture would be stuck out in the desert, pinned down with your eyelids cut off, so you can’t shield from the sun, and covered with warm honey next to an ants nest. The honey will burn… eventually. And you’ll soon have piles of dust in your eye sockets.
Or trapped in a room, lying down, with a drip of water hitting you in the forehead once every 2 seconds. You would go absolutely MAD and a hole will drill through your head if left long enough…