Someone mentioned this clip, so I am posting it:
View attachment Getting tickled upside down.mp4
I think upside down tickling is quite hot, because it adds to the feeling of helplessness, emphasizes the breast and opens the face for easy "underfoot humiliation." Unfortunately, the feeling can be quite unpleasant after while, with all the blood rushing to the head. I only tried it twice, once on my girlfriend, and another time when we tickled another girl together. We found a workaround the inherent limitations of the process by limiting it to short periods of 1-3 minutes (we made the tickling really intense to compensate). It was quite awesome when she put her bare foot on our friend's face and asked her to kiss it if she wanted to be propped back up
There is also something that I love to do. Sometimes when my girlfriend is lying on the bed, she lets part of her body like her upper torso hang over the edge, usually when she want to grab something on the ground like her phone. There have been a couple of times when I jumped on her, straddling her hips to prevent her from moving, and tickled her already stretched upper body. She can't fight the tickling too much because she feels she is going to fall, and the feeling of desperation is a big turn-on for both of us.
An alternative that I haven't tested: instead of the raw vertical 90° upside down hanging, maybe tying up the victim at a softer angle, say 45° with her head lower than her feet (like for waterboarding) would achieve the desired helplessness without the adverse effect of the "blood rush"? Does anybody have any input on the matter?