If it's gelatin, I think you would die. Your body weight would break through the surface tension of the gelatin, so you'd go crashing to the bottom of the vat -- and there you would die of asphyxiation, because even though you were heavy enough to break through the gelatin, it would seal back up above you -- and close off your access to oxygenated air. :|
Now, if by "Jell-o" you meant pudding or custard, then (1) hell yeah! and (2) http://www.youtube.com/watch?v=ed1Ucnvn08s (skip ahead to 2:10)
I would like to have sex in a big tub filled with ...Japanese schoolgirls. erfectplan:
or isn't that a viable answer.... uzzled: