Can you reveal your hand when you fold in poker?

Question

In some situations in poker it might be beneficial to reveal my hand when I fold.

Is it allowable to do this, or must the contents of a folded hand remain secret?

Answer 1

No, you are not allowed to show reveal your hand when you fold as that gives unequal and unfair knowledge to the rest of the players. For example in Texas holdem where you have two cards in your hand it would reveal to others two cards that would not possibly show up in the cards on the table and that could give them knowledge that they need in order to fold or bet to their advantage.

http://poker.wikia.com/wiki/Fold

Folding should be done without revealing your cards. To do otherwise is against the rules and is considered rude in poker etiquette. If a player folds their hand face up, the other players get additional information about what cards are dead and what cards are still live, and this additional information may affect later betting or game play (a player on a draw may subsequently fold if they see another player fold one of their outs face up, for example). If a fold is done in such a way that only some players at the table could see the cards being folded (e.g. they flipped up on edge, facing one end of the table, then fell back facedown), the dealer is responsible for ensuring that all players have an equal opportunity to know what cards were folded. If a still-active player suspects that some other player has seen a folded card, they may request the dealer to show it to everyone, under the common "show one, show all" rule. Generally speaking, however, hands which are folded by a player are not shown to other players, and other players do not have a right to see them.

In variants with upcards such as 7-Stud, folding is done by first turning your upcards over, facedown, and then returning them to the dealer or the muck. Note that in these variants, it is often against the rules (and is always inconsiderate) to fold out of turn, since hiding your upcards prior to someone being able to act deprives them of information which other players may have seen.