Remember, the 'customer' is always right. [=never argue with a customer]
He is one tough/tricky 'customer'. [=he is a tough/tricky person]
The company has good/poor 'customer' service.
(..) won't give you the diamonds? A store like this is insured up the ass. They're not supposed to give you any resistance whatsoever. If you get a customer or an employee who thinks he's Charles Bronson... smash their nose with your gun. Drops him right to the floor. Everyone jumps. (..)1992 Reservoir Dogs