bet (one's) life(redirected from bet their life)
bet (one's) life
To be totally certain that something is the case or will happen (so much so that one would hypothetically risk one's life betting on it). I just know that Tom is innocent. I'd bet my life on it! Oh, you can bet your life that Kevin will be late tonight—he's never on time!
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.