竹马之交

Explanation: When a child might ride a bamboo pole bamboo horse. Would a good childhood friend. 　　Usage: Partial official; as object; with compliment 　　Source: Tang Li Bai, "Ezra," Lang bamboo horse to ride, get around the bed plum, cohabitation thousands of miles long, two small non-suspect guess. " 　　Examples: He and Cai Wenji is ~, they are too intimate. ★ Guo "Wenji" fourth act first Thesaurus:  Erbinxiangmo, be very much in love, Childhood, Pigeon Car Zhuma, two innocent playmates, s hair twisted in a knot companion in adversity, parental betrothal; the two (the boy and the girl) had been engaged to each other before they were born, Hobbyhorse Friends