Sign your own death warrant - Idioms by The Free Dictionary
sign your own death warrant
sign (one's) own death warrant
To knowingly do something that will bring one trouble, punishment, or harm (and perhaps literally one's death). If you stay out past curfew again, you know you're signing your own death warrant, right? Testifying against the mob boss is like signing your own death warrant.
sign your own death warrant do something that ensures your own demise or downfall.
sign your own ˈdeath warrant do something that results in your own death, defeat or failure: By refusing to play pop music this new radio station is signing its own death warrant.