save someone's ass
save (one's) ass
rude To rescue someone from failure, danger, or disaster; to prevent something bad from happening to someone. Thanks for bringing me some extra cash—you really saved my ass, there! The company is in dire need of new investors to save their ass.
save someone's assor
save someone's buttmainly AMERICAN, INFORMAL, RUDE
If you save someone's ass or save their butt, you save them from a dangerous or unpleasant situation. Howard rushed up to me and said, `Thank you, thank you, you saved my ass.' You should be grateful — I saved your butt! Note: You can also say that you save your own ass, meaning that you escape from a dangerous or unpleasant situation. She climbed out the back of the car to get away, to save her own ass.