(informal) not to believe one's ears

(informal) not to believe one's eyes

(figuratively, informal, of people) not to line up, not to queue up, not to crowd in, not to fall over each other (with the implied meaning that something meets with little success)

(informal) not to be faint-hearted, not to be backward in coming forward, to have guts, to have plenty of nerves

to show no sign of life, not to let people know that one's alive

(informal) it doesn't cost anything, it can't hurt

(informal) not to be out of the woods yet, not to be in the clear

plenty is no plague, you can never have too much of a good thing

Synonym of ne pas en foutre une

Dated form of ne pas se fouler.