I've folded it once. Here was the action, as I recall
Donkey in EP: Raise to 8 (i believbe I was playing 1/2 NL)
ME: KK Reraise $24
Player to my left: All in $198
SB: CALL
I knew that the donkey could have anything, the player who pushed in IMO had AT LEAST JJ, but more likely QQ KK (unlikely) or AA
For the SB to call all this action he has to have at least KK (unlikely) otherwise AA
I folded (oh yea the donkey called too but that wasnt a concern)
Donkey: AJo
Player to my Left: KK
SB: AA
now thats some interesting deal pokerstars....