The first time you take all the other players chips and you are the last person at the table, this trophy will unlock. If you are not familiar with the rules of poker, you can go all-in every hand and then use the PS3 button to exit to the dashboard if you don't have a winning hand once the 5th card hits the table.
On the top of the screen is a list of the player names. If at the end of the hand your name does NOT show the 100% total, press the PS3 button to exit to the dashboard and try again.