The word 呲牙咧嘴 is formed by combining the two actions 呲牙 (baring teeth) and 咧嘴 (grinning widely), where 呲 means to expose, 牙 means teeth, 咧 means to stretch open, and 嘴 means mouth; together, they literally describe the simultaneous act of showing teeth and opening the mouth wide, typically depicting a grimace or snarl.