Okyakusama wa kamisama desu: the customer is god. The line is famous as the words of the singer Minami Haruo. In his book Kagei no tenchi of 1984, he explained that in this sense the audience is a gathering of absolute beings, and that he had been taught that the absolute between heaven and earth is god.
His daughter, Minami Miyuki of his management company, says that the true meaning of the phrase is entirely different from its use today in cases of customer harassment.