Where did the Emperor of Heaven, Emperor of Earth, and Rakshasa lying in the back kitchen come from?

The proverb "The emperor is emperor, the emperor is emperor, and the Rakshasa is lying in the back kitchen" comes from the ancient Chinese joke drama "The Romance of the West Chamber". "The Romance of the West Chamber" is a classical novel with the color of a comic skit, written in the late Yuan Dynasty and early Ming Dynasty. The book is divided into three chapters, telling the love story of the protagonist Li Shishi and his new wife Wang Cuicui, as well as the interesting stories with his neighbor Zhang Sheng. "The emperor of heaven, the emperor of earth, the Rakshasa is lying in the back kitchen" is one of them. The content is: A Rakshasa (a kind of vampire monster) entered the kitchen of Master Li's house. Zhang Sheng heard about it and came to fight the Rakshasa. Zhang Sheng shouted "Emperor of Heaven, Emperor of Earth" and used the pot lid as a weapon to chase Rakshasa and drive Rakshasa out of the kitchen. This sentence expresses contempt and ridicule for the evil Rakshasa monster through Zhang Sheng's exaggerated and funny actions.