The Eight Characters indicate the year, month, day and hour of a person’s birth, which are often used in fortune-telling in China. It usually appears in four pairs, each consisting of a tiangan 天干 [heavenly stem] and a dizhi 地支 [earthly branch]. In ancient China and also sometimes in modern China, the eight characters of the unmarried couples will be taken to fortune tellers to see whether marrying each other is a good decision. Exchanging the Eight Characters between the two families is therefore an important step of the marriage. Hence, here this phrase actually means “How could Zhanghua be willing to marry someone so carelessly?”