咧嘴
liě zuǐ · HSK 7
to grin
😁 咧 (open the lips) + 嘴 (mouth) = pull your mouth open wide, i.e. to grin
嘴 zuǐ is the everyday word for mouth. 咧 liě means to part or stretch the lips sideways, so 咧嘴 is literally widening the mouth — the face you make when grinning. The 口 radical on the left of both characters flags them as mouth words.
嘴 — mouth 口 + 此 (phonetic) + 角 (horn)
嘴 is a semantic-phonetic compound. The 口 (mouth) component gives the meaning, while 觜 (originally 'beak/horn-tip', combining 此 and 角) supplies the sound. It first meant a bird's beak, then broadened to mean mouth, and by extension the spout or tip of any object.