Ha, it's crossed my mind a few times! I've had a few MRIs in the past and each time while having it done, I did think how easily it would be for the technician to tickle me, but they never did. I know a lot of people feel anxious or claustrophobic, but I find helpless, confined spaces like that either comforting or exciting. I wouldn't say I have any real medical fetish or anything, but there are a lot of medical scenarios that leave one vulnerable that are exciting to me in the context of tickling.