not on your life

Not on your life! {infml} (a phrase used to mean that something absolutely will not happen under any circumstances, even if one is facing death) — Ни за что (на свете)! Ни в жизнь!

Used to strongly oppose /refuse someone's suggestion or request.

"So you're going to bring Kev, are you?" "Not on your life!"

"You’ll never tell anyone what happened here today, right?" "Not on your life!"

Related expressions:
[ни за что на свете]