Idiom of the day :- Cool customer

Usage, examples and definition of the Idiom :-

this idiom has nothing to do with a customer — and it has nothing to do with a customer lacking warmth. That’s because a cool customer is someone who is calm, completely in control of himself, and shows little emotion. Being relaxed under pressure is this person’s distinctive quality. ‘With no display of fear, Harry traveled all the way to the North Pole alone. He sure is a cool customer.’