Martingale
This is a betting system that has the player doubling there wager after each loss. This is called a negative betting progression and it is very dangerous. While theoretically sound the player can quickly reach the table limit or exhaust their bankroll before winning a wager. This progression works like this (first wager $5, then it's 10, 20, 40, 80, 160, 320, 640, 1280, 2560, 5120, many table limits cap-out at $300)