Su Dongpo's sister Su Xiaomei is a talented woman. It is said that the groom, Qin Shaoyou, was shut out on their wedding night, and only when she asked him to write couplets could she enter. The first part of Su Xiaomei's publication is "Behind closed doors, shoot the moon to the window". Qin Shaoyou thought for a long time, but he didn't come up with the bottom line. Su Dongpo saw it. He was worried about his brother-in-law, but it didn't help. Looking at the pond in the moonlight, he suddenly had a brainwave, picked up a stone and threw it into the water. Qin Shaoyou saw it, and immediately called down to "throw stones at the underwater sky".