Christopher Robin is a character created by the writer A. A. Milne in his Winnie-the-Pooh books. He is a small boy, sometimes shown wearing a yellow raincoat or mackintosh. He enjoys going on adventures and especially loves the zoo.
Louise refers to the narrator as 'Christopher Robin' because s/he is wet from the rain. However it is interesting to note that s/he is being addressed by a boy's name.