if (one's) life depended on it

if (one's) life depended on it

Under any circumstances; no matter what. (Used almost exclusively with a negative statement regarding something that one couldn't or wouldn't do.) No way am I going to karaoke night. I couldn't sing if my life depended on it! No thanks, I wouldn't see that film if my life depended on it.See also: depend, if, life, on