[mcguw]

This is a clear fold. SB just bet $300.00 into a $125.00 pot. Unless he is a maniac, there is no way he would do that with any hand less than a set or a straight. Most likely he was trying to push off the flush draws, which makes me think a straight is more likely. If he had a set, he is slightly worse than 1:2 to have the board pair to make a boat (or 4 of a kind) by the river and there is almost 2:1 against a flush hitting. I could be wrong, but a huge bet with a hand which is probably the best and could still easily improve to best, does not seem logical. On the other hand, the nut straight is far more vulnerable to a flush draw, so it would make more sense that he would overbet the pot. Also, he would have to be pretty sure that he was not currently beaten to make such a huge bet. Hence, with him most likely holding the nut straight, he would call your push. Unless you caught runner runner, you just lost your stack. Clear fold.