to save your life

couldn't (do something) to save (one's) life

slang Cannot do something well or at all. Ugh, this art assignment is so annoying—I couldn't draw an apple to save my life. Rachel is so selfish! She couldn't consider another person's feelings to save her life.
See also: life, save

to save (one's) life

Regardless of one's effort, passion, or desire. Used after a negative verb construction to emphasize one's inability to do it. 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 couldn't consider another person's feelings to save her life.
See also: life, save
Farlex Dictionary of Idioms.

to save your life

used in various expressions, especially can't (or couldn't ) do something to save your life , to indicate that the person in question is very incompetent at doing something.
The first recorded use of this expression is by Anthony Trollope in The Kellys and O'Kellys ( 1848 ): ‘If it was to save my life and theirs, I can't get up small talk for the rector and his curate’.
See also: life, save
Farlex Partner Idioms Dictionary
See also:
  • can't (do something) to save (one's) life
  • can't do something to save your life
  • back at it
  • back at it (again)
  • butt-wipe
  • apple-knocker
  • can't stand
  • can't stand (someone or something)
  • be on somebody's back
  • be on someone's back
References in classic literature
Take my advice, therefore, and if you wish to save your life follow some other path.'
I will make you a present of them both, as I am anxious to save your life; but you must leave your horse behind you, for it would stumble over the fallen trees or get entangled in the briers and thorns.