im going to go with what several others have already said and say myself ^_^ at NEST i was in a X frame getting it pretty good, and my ler was going between me and somebody else, so i was standing their, bound and watching and waiting for the torment to return to me, and i couldnt get enough. there was no torture feeling, it was too much fun. i was squirming so much i was hitting my head on the sides of the frame and i didnt even care, it was just so awesome. my 1 arm was actually hurting pretty bad from lack of blood flow, and was getting pretty cold, at which point she decided to stop so i didnt get hurt....i still wanted more though, lol. after a few minutes i was bugging somebody else to strap me to a device much like the red devil seen in some videos, lol. too bad it didnt happen though.
basically, though, to add to the topic: a person who when being tickled, feels no torture, no matter how intense it is or how long it is happening, will continue to want more. someone who will ignore their bodies natural reaction to an uncomfortable situation, all for the sake of getting as much of the addicting feeling of being tickled, as possible.