清康熙初年，原广西罗城县令于成龙升任合州知州，离开罗城时，竟然连赴任的路资也没有。其子从山西老家来看他，临走时他含泪对儿子说：为父本来想为你准备一盘缠，可为父是身无分文呐，你把这半只鸭子拿上，路上吃吧，虽解不了远渴，却也可以充充饥。儿子十分理解父亲的处境，含泪向父亲告别。这件事情很快就被流传开来，于成龙也被冠以“半鸭知县”的称呼。

In the early years of Emperor Kangxi in the Qing Dynasty, Yu Chenglong, the former magistrate of Luocheng County, in Guangxi Province, was promoted to prefect of Hezhou Prefecture. When he left Luocheng, he even had no money to go to his post. His son came to visit him from their hometown Shanxi Province. On departure, Yu tearfully said to his son, “I’d like to provide travelling expenses for you, but I’m also penniless. So take this half duck and eat it on the way home. Although it won’t make a big difference, it can still relieve your hunger”. His son was very understanding about his father’s situation and bid farewell to him with tears in the eyes. This anecdote was soon widely spread, and Yu Chenglong was dubbed as “the Half Duck Magistrate”.