闭嘴 (bì zuǐ) literally means close mouth. 闭 (bì) means to close or shut, and 嘴 (zuǐ) means mouth. Used as a direct command it is the Mandarin equivalent of shut up and carries a rude or sharp tone. It can be softened slightly in certain contexts (请闭嘴, please be quiet) but generally signals frustration or anger. Common in colloquial speech and dialogue-heavy contexts.