I lived in Metz, in Lorraine, where St Nicholas Day is a serious celebration! I remember the schools being closed and a wonderful procession taking place through the town, with floats, lights, music and fireworks.
The most popular St Nicholas story tells of three children who have wandered off and become lost. Cold and hungry, a wicked butcher lures them into his shop where he attacks and then salts them in a large tub. Through the intervention of St. Nicolas the boys are restored to their families.
This story led to Nicolas being recognized as the protector of children. The evil butcher became Père Fouettard, who has followed St Nicolas in shame ever since. Le Père Fouettard, translates literally as “the whipping Father’. According to legend, he was an evil and menacing figure who accompanied St. Nicholas, when visiting the homes of children. In contrast to St. Nicholas, who presents good children with treats and gifts, Père Fouettard, either gives lumps of coal or spanks the naughty children. His menacing appearance combined with his ill-nature, frightens children and prevents them from doing bad things. It is also believed that Père Fouettard tells St. Nicholas, which children have been naughty during the year, and consequently, they are deprived of any treats!
With thanks to: http://www.stnicholascenter.org/pages/france/
Follow this link if you want to find out more about St Nicolas.