The expression comes from the cheo play Thi Kinh, the Goddess of Mercy (Quan Am Thi Kinh). Thi Kinh and her husband, Thien Si, are a well-matched and happy couple. One night the husband falls into a deep sleep after hours of studying. As Thi Kinh fans him, she discovers an ingrown facial hair, which is considered an ill omen. Since she does not want to awaken him, she quietly takes a knife to his neck to remove the ingrown hair.running; they accuse Thi Kinh of attempted murder, She is banished from her in-laws' house. Grieving, she disguises herself as a man and becomes a "monk" with the religious name of Kinh Tam at Van Tu Pagoda.
A girl named Thi Mau, the daughter of a rich family, lives near the pagoda. She mistakenly believes that the new monk is a man, falls in love with "him," and visits the pagoda often to catch a glimpse of "him." She flirts shamelessly with the monk, but "he" does not respond to her overtures. Disappointed by the monk's rejection, Thi Mau returns home to seduce her house servant, No. She becomes pregnant.
Village custom requires that unmarried pregnant girls be punished. Thi Mau accuses Kinh Tam of being the father. On the basis of these accusations, the superior monk drives Kinh Tam out the front gate of the pagoda. After Mau delivers, she abandons the baby at the pagoda gate. Kinh Tam is compassionate and takes up the newborn to beg for milk from nursing mothers. The baby survives and grows to adulthood. One autumn evening, Kinh Tam dies, and the truth of her gender is revealed. Everyone discovers that the charges against her are unjust.
This is a model cheo play in plot and "life bits." It is also a good example of the secularisation of Buddhist tales.