tough as nails

bite one's nails

To worry or fret over something.

do it tough

To be in a desperate situation; to struggle.

hang tough

To remain strong-willed or brave, especially when experiencing duress or adversity.

hard as nails

Very unsympathetic; callous

spit nails

To speak or sputter in a very angry manner.

squint like a bag of nails

To squint very much, as though one's eyes were directed as many ways as the points of a bag of nails.

tough break

A situation resulting in misfortune or hardship; an instance of bad luck.

tough call

A choice or judgment which is difficult to make, especially one involving only two alternatives.