Fig. to endure something unpleasant without fighting back. He insulted me publicly. You don't expect me to take that lying down, do you? I'm not the kind of person who'll take something like that lying down.
Submit to an insult, rebuke, or other harsh treatment without resisting, as in He won't take that snub lying down. This idiom uses lying down in the sense of "passively." [Late 1800s] Also see take it, def. 2.