Sing-song girls (also known as flower girls) is an English term for the courtesans in nineteenth century China.
Before the founding of modern China in 1911, concubinage was legal. In Chinese custom, males carry the family name and the family's heritage after marriage. To ensure male heirs were produced, it was a common practice for an upper-class married male to have one or more concubines, provided he could support them.
The custom could be invoked without the wife's consent: the husband's actions were protected by law. Concubines would co-exist in the family along with wives and children. A man might choose a courtesan to be his concubine. Many of these courtesans would sing songs to attract potential husbands, hoping to become secondary wives.
Western observers in China during the nineteenth century witnessed these women singing but had no idea what to call them since they were not classified as prostitutes. Thus the term "Sing-Song Girls" came about.
There is another version of the source of the term. According to the 1892 fictional masterpiece by Han Bangqing called Sing-Song Girls of Shanghai, also known as Flowers of Shanghai, people in Shanghai called the women who performed in sing-song houses "xian sheng" (Chinese: 先生) in Wu language. The term was pronounced like "sing-song" in English and the young women always sang to entertain the customers; thus Westerners called them Sing-Song girls. The word sian sang in this case is a polite term used to refer to an entertainer.
Sing-song girls were trained from childhood to entertain wealthy male clients through companionship, singing and dancing in special sing-song houses. Not all performed sexual services, but many did. They generally saw themselves as lovers and not prostitutes. Sing-song girls did not have distinctive costumes or make-up. Often they wore Shanghai cheongsam as upper-class Chinese women did. Sing-song girls often performed amateur versions of Chinese opera for clients and often wore the traditional Chinese opera costume for small group performance. The girls had one or several male sponsors who might or might not be married and relied on these sponsors to pay off family or personal debts or to sustain their high standard of living. Many sing-song girls married their sponsors to start a free life.