The idea of doubling your bet every time you lose is known as the Martingale betting strategy. While it may seem like a guaranteed way to eventually win, there are significant risks involved.
phrase. You use expressions such as 'I bet', 'I'll bet', and 'you can bet' to indicate that you are sure something is true. [informal] I bet you were good at games when you were at school. I bet you anything you like he's a pimp.