The power of 不要脸 (bù yào liǎn) is impossible to grasp without understanding the concept of 面子 (miànzi), or “face.” In Chinese culture, “face” is a combination of a person's social standing, reputation, influence, and personal dignity. Maintaining one's own face and giving face to others is fundamental to social harmony. There's a crucial difference between “losing face” (丢脸, diūliǎn) and “not wanting face” (不要脸, bù yào liǎn):
Comparison to Western Culture: While “shameless” is the closest English equivalent, it lacks the deep cultural weight. In the West, “shameless” can sometimes have a neutral or even slightly positive, rebellious connotation (e.g., “a shameless self-promoter” can be seen as a savvy businessperson). 不要脸 is never positive. It is a severe condemnation of someone's moral character, rooted in the collective value placed on reputation and social honor.
不要脸 is a highly informal and very strong insult. It should be used with extreme caution, as it can escalate a conflict significantly.
It is almost exclusively negative and used to express disgust and contempt. Never use it in a formal setting or with someone you need to show respect to, like a boss or teacher, unless you are prepared for severe consequences.