"Don't hit one on the face; Do not grab one¡¯s spoon from his mouth. "
Da3 ren2 bu4 da3 lian3; chi1fan4 bu4 duo2 wan3.
Disclose one's shortcomings in public would only antagonize him. Be diplomatic or tactic and he may accept your criticism.
"A donkey has limited abilities. "
Qian2 lü2 ji4 qiong2
The story goes that when a tiger sees a donkey for the first time it does not know whether the donkey is a threat. After a few teases, the tiger learned the limits of its ability. The result is apparent. The proverb is used to refer to someone who has exhausted his limited ability. Never use this proverb with your colleague or friends. It is derogatory: the slight of donkeys seems universal.
"Donkey's lips do not fit in with a horse's mouth."
Lü2chun2 bu2 dui4 ma3zui3.
It refers to something totally irrelevant.