There is a legend that the story is too long. It is probably that there was once a fairy who came down to earth and married a mortal forever. Later, the Jade Emperor sent heavenly soldiers to catch fairies, and then he caught people. The man couldn't scratch the bottom of the pot or wipe his face, so he ran away. Later, to commemorate, he smeared the groom. After a long time, his parents and elders wiped it.