Su Dongpo, a great writer in the Song Dynasty, was fond of crabs, and often exchanged poems for crabs: "You can laugh at Wuzhong's greed and obedience, and one poem is exchanged for two sharp groups (crabs, called sharp groups in ancient times)." The literary giant changed two crabs for a poem, triumphant. No wonder, after eating crabs, he sighed: "If you don't eat crabs, you will live up to your vision." .