"Skip to My (The) Lou was a popular partner-stealing dance from America's frontier period. Since instruments were frowned upon, particularly the fiddle, the dancers had to create their own music by clapping and singing.
Couples would dance around a lone male who sang "lost my partner, what'll I do." At the appropriate point in the lyrics, he would "steal" the partner of a dancing man as he sang "I'll find another one prettier than you." The displaced man would take his place in the circle.
"Lou" is apparently a corruption of "loo," the Scottish word for lovecitation needed.
An unconventional arrangement of this tune is featured in the 1944 motion picture, Meet Me in St. Louis.