Double or nothing
Double or nothing[1] (UK often Double or quits) is a gamble to decide whether a loss or debt should be doubled.
It refers to the potential outcome in a betting situation where the winner risks what has been won for a chance to double their winnings. If the loser of the initial bet loses the second bet then they owe double. For example, if one owes somebody a bottle of Coke from a bet and then places a "double or nothing" bet with the same opponent, they will owe two bottles of Coke if they lose and will owe double if they win.
Poker
In poker, a double or nothing tournament is a sit'n'go tournament where the surviving half of players gets double the buy-in and the eliminated half does not receive any prizes. Double or nothing tournaments are mostly played by ten players (five players win) or six players (three win), although multi-table versions, such as for 20 players, exist. The rake in these tournaments is usually smaller than in standard sit'n'go tournaments. Some poker rooms also offer triple or nothing tournaments, where one third of the playing field gets paid.