I have watched people being fisted... if you can imagine the look of pain/joy/whatever on the person that has another mans arm buried up to the elbow in his ass and guts.... think about how they must feel... now multiple that by 10x and you will see what these people doing sounding appear to be going through.
I mean, they just collaspe. Most are sitting down in a chair and they instantly like turn to water, no bones in their body and just flow out of the chair to the floor and twitch around like a seizure.