can't do something to save your life
can't (do something) to save (one's) life
slang Cannot do something well or at all. Ugh, this art assignment is so annoying—I can't draw an apple to save my life. Rachel is so selfish! It's like she can't consider another person's feelings to save her life.
can't do something to save your lifeSPOKEN
If you say that you can't do something to save your life, you mean that you cannot do it at all. I'm never nervous at exams but I can't study to save my life. He can't sing to save his life but he's a good guitarist.