[UncleSalty]

I don't think I like this at all. CO's bet might not mean anything, but BB's raise on the flop almost certainly means a 9 or pocket pair.

Against 3 players who have already called on a paired flop in the face of aggression, you are checkraising the field with nothing but two overs. BB is clearly not going anywhere, I would say he has to have either A9 or a pocket pair TT or above and is afraid to raise with the 5's on the board. Once you get two callers on the turn, I am done with the hand unless you improve on the river. (And I might just c/c a river A or Q.)

Edit: Reviewing the PF action it is unlikely that BB has a premium pair, but he could have A9, TT, 99, 88, 77, or 66 and play it this way.