嘴 + Verb (in idiomatic expressions)
嘴 (zuǐ) is a noun meaning "mouth." It refers to the physical body part and is also used in figurative expressions related to speaking. For example, 嘴说腿跑 suggests that one should back up words with action.
你嘴上说不饿,身体很诚实啊。
Nǐ zuǐ shàng shuō bù è, shēntǐ hěn chéngshí a.
You say you're not hungry, but your body is being honest.
小朋友的嘴上沾满了巧克力。
Xiǎopéngyou de zuǐ shàng zhān mǎn le qiǎokèlì.
The little kid's mouth was covered in chocolate.
他张开嘴想说什么,又闭上了。
Tā zhāngkāi zuǐ xiǎng shuō shénme, yòu bìshàng le.
He opened his mouth wanting to say something, then closed it again.