How did Coco Chanel get the nickname coco?

She adopted the name Coco during a brief career as a cafe and concert singers 1905-1908. First a mistress of a wealthy military officer then of an English industrialist, she drew on the resources of these patrons in setting up a millinery shop in Paris in 1910, expanding to Deauville and Biarritz. The two men also helped her find customers among women of society, and her simple hats became popular.