It should come from "Liezi·King Mu of Zhou", which is the allusion of the commonly said "Deer Dream" or "Jiao Dream"
"The people of Zheng who have a salary in the wilderness will encounter dangers." The deer, trying to catch it, killed it. Fearing that people would see it, it suddenly hid in the gods and covered it with bananas. They were so happy that they left it where it was hidden, so they thought it was a dream and chanted it along the way. When someone heard about it, he picked it up with his words. When he returned, he told his family members: "The person who asked for the salary dreamed of finding a deer and didn't know where it was. I found it now, and it was really a dream." He said, "What if I dreamed of a deer? Is it true that I got a deer now?" My husband said, "I have a deer, so what's the use of knowing that I dreamed of a deer?" ? "The return of the salaryman is not tired of losing the deer. He dreamed of hiding the deer at night. He found it in the dream and returned to the court." The master said: If you really dreamed of getting a deer, you would think it was a dream. If you really dreamed of getting a deer, but if you compete with Ruo for a deer, the people in the house would say that no one has a deer. According to this deer, please share it in half. "It means that the gains and losses in the world, honor and disgrace, are all impermanent.
PS: Tan Chun's nickname in "A Dream of Red Mansions" is "Jiao Xia Ke", and Tan Chun is laughed at by Dai Yu. It is a deer, and this is also the allusion.
Lu You's "To the Hermit in the Mirror": "The deer dream has returned to its original state, and the sound of the barking mastiff is still loud."
Jia Xuan himself also used: "Banana Deer" Dream, draw a snake cup. The yellow flowers are haggard and windy, and the wild green is blooming. "