re: Poker & .25/.50 LHE 10 handed: third pair in the BB on the flop
I would check/fold. You have a weak hand that is probably not best out of position in a small pot. A bet from you is not going to fold out an ace, and given your table image, a Jack will probably peel one off too, especially since the most likely Jacks will have some sort of straight draw to go with it (KJ, QJ), if not 2 pair already (AJ, JT). You also may be getting crushed by KT or QT, neither of whom is likely to fold either.
Maybe if it gets checked through and a blank falls on the turn you could take a stab, but I probably wouldn't even do that either, given this board.