The Little boy who lived down the drain
(Book)

"Sally loved taking baths. It wasn't because the water was full of bubbles ... or because she had the bathroom all to herself ... and it was not because she always came out squeaky clean ... Sally loved taking baths because it was the only time she could talk to the little boy who lived down the drain. Sally found out about him when her mother sang to Sally's baby brother about Baa Baa Black Sheep and his three bags of wool ... one of which went to the little boy who lived down the drain. And thus a friendship was born. Every bath that Sally took was devoted to finding more out about her new friend."--Amazon.com.