Su Shi once called Cheng Yishu Sun Tong.

As Professor Wang Shuizhao mentioned in his book, the smelly duck back is the name of a swamp outside Bianjing, and "smelly duck" means unclean. Uncle Sun Tong in Beili means fake uncle Sun Tong from a dirty place. It is in sharp contrast with Uncle Sun Tong's image of making court ceremonies and lifting the court purges, thus achieving ironic effect. Su Shi himself once called himself "Taojing Festival in Yaochi Beili" and said that he was an unqualified Tao Yuanming.