Sensory Deprivation
The majority of those I encounter in my dungeon want to experience all of their senses at once. Others take delight in having some or all of the sensory experience taken away from them. I can use a variety of toys and scenarios to accomplish this: hoods, gags, blindfolds, duct tape, plastic wrap, ear plugs, and breathing tubes.
Mummification with plastic wrap and duct tape can effectively shut you off from the outside world. It's a very intense experience not recommended for the novice player, but a real head trip for those who understand their limits.