Chinese Adages tells us the supposed derivations of some Chinese idioms, including:

• Pat the back of the horse became a colloquialism meaning to flatter somebody thanks to the odious eunuch Wei Zhongxian who became successful after winning the emperor's favor by patting rather than whipping his horse.



• Blowing Into the Cow Hide (bragging) comes from people who used their "hot air" to blow up hides to make rafts.



• Eating Vinegar (meaning being jealous of a rival in love) comes from a story about Wei Zheng's wife who drank vinegar that she thought was poison when told he was going to have a concubine.