Post Oak BluffA post oak bluff is made by placing a small bet just before the showdown to give the appearance of a suckbet. The opponent is to believe that he is being offered a cheap way to see the showdown, that he is meant to stay in the hand to be beaten by a strong hand. Having reached this conclusion, he will fold. If the bluff works, it is a cheap way to win a pot.
A post oak bluff is viewed as useless by many players because the small bet will lead to the opponent having such good pot odds that he calls instead of folding. On the other hand, it doesn't have to work very often since it has a good cost/benefit ratio.