"Take lying down" is a phrase that means to accept or tolerate something, usually negative, without fighting back or taking action against it. In terms of antonyms, some words that come to mind are resist, fight back, challenge, or oppose. Instead of accepting something passively, these antonyms suggest actively pushing back against it, standing up for oneself or one's beliefs, and taking a more assertive approach. Other possible antonyms could include rebuff, reject, disapprove, refute, or deny, all of which imply a complete rejection of something rather than simply tolerating it. By employing these antonyms, individuals can empower themselves to take action and make positive changes in their lives.