[RobA]

seems like you already came to your conclusions about this. i guess you found out you were behind when CO 3-bet the entire field on the flop, so call, as the odds justify on the flop. and the same on the turn.

on the river i can't find any combo of hands that you beat, but i still don't even know if that is good enough info to fold for 21-1. we are human beings, not robots, so we do wierd things sometimes. the question is how often is that? probably a lot less than the 5% needed to call, so I guess its a fold.

i guess SB had TT, and CO had AA and was looking for an overcall?