What does it mean to ride a bamboo horse to pick up childhood?

childhood friends, one of Tang Li Bai's Long March: "when you, my lover, on a bamboo horse, came trotting in circles and throwing green plums. We lived near together on a lane in Ch'ang-kan, both of us young and happy-hearted. " Later, "childhood friends" were used to describe the situation between boys and girls. Ou Yangyuqian's Peacock Flying Southeast Scene 4: "You and I have been in love since childhood, and we have no guess since childhood." 1. Plum: green plums; Bamboo Horse: Children ride horses with bamboo poles. Describe how innocent children play games. Out of one of Tang Li Bai's Long March: "when you, my lover, on a bamboo horse, came trotting in circles and throwing green plums. We lived near together on a lane in Ch'ang-kan, both of us young and happy-hearted. " Later, "childhood friends" were used to describe the situation between boys and girls.