It has something to do with the legend of Nuwa Empress. According to legend, Nu Wa Niangniang made up good people and found that people gave birth to children on the ground, and all kinds of plagues came to harm these children. Seeing this, Nu Wa was very angry. These atheletes of plague dared to harm her offspring. She finally defeated these plague gods who spread diseases everywhere.

But in order to avoid hurting the people again, she told them that every day in the long summer, adults must eat eggs, and children should hang all kinds of boiled eggs on their chests, so as to avoid the plague from making trouble again.

Sure enough, after listening to Nu Wa's words, the people eat eggs every long summer, and the children have eggs hanging on their chests. Everyone spent a quiet time in the long summer. Later, the custom of "eating eggs in long summer and not suffering from summer heat in hot days" was handed down.