Originally Posted by FlyingSaucerAttack
I believe there was a post earlier here on this. I was also confused about this until recently when it was answered.
It is true that it is OK for some to not show their cards and forfeit the pot.
The rule that governs this has to do with who did the last bet into the pot. Folks with more experience in live play please correct me if I am wrong.
So, here are examples involving just 2 players.
On the river, player 1 checks, player 2 bets, player 1 calls. Player 2 must show his cards first, and if player 1 wants to he can muck his cards and forfeit the pot to player 2. Otherwise, if player 1 wants to claim the pot he has to show his cards.
This is because player 2 did the last bet, and player 1 only called. (ie, player 2 is the one who increased the "stake" in the pot.)
Here's another. Player 1 and 2 again. Player 1 bets preflop. Player 2 calls. Player 1 bets the flop, player 2 calls. Player 1 bets the turn, player 2 calls. Player 1 bets the river, player 2 raises, player 1 calls. Player 2 must show first because he did the last bet into the pot. Player 1 can decide to muck or show.