Not on your life
Definition 1 of 1
Pro Tip 1/3Strong Refusal
Use it to express a very strong or emphatic refusal or rejection of a suggestion. 
"Would you like to try insects for dinner?" "Not on your life!"
Pro Tip 2/3Emotional Emphasis
The phrase adds dramatic effect and shows you have strong feelings about not doing something. 
"Are you considering taking that risky job?" "Not on your life!"
Pro Tip 3/3Informal Setting
It is casual and used more commonly in spoken English or informal writing, like text messages. 
"Can I borrow your car for the road trip?" "Not on your life, it's brand new!"