不要脸 is a colloquial fixed phrase meaning 'shameless, brazen'. It is far stronger than the literal translation 'don't want face' — it's a harsh accusation used to condemn someone's immoral, audacious, or socially unacceptable behavior. In daily speech, it's often uttered as an exclamation (真不要脸!) or embedded in a sentence to describe someone's brazenness. Avoid using it in formal writing or polite contexts.