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.
(..) – Like that! – My good man, I'm simply trying to ascertain- – Speak English, goddammit! SCHULTZ: Everybody calm down, I'm simply a customer trying to conduct a transaction. – I don't care. No sale. Now off wit' you! – Oh, don't be ridiculous, (..)2012 Django Unchained