Why is "It Looked Like Spilt Milk" trending?

Wikipedia Overview

It Looked Like Spilt Milk is an American children's picture book, written and illustrated by Charles Green Shaw. Originally published in 1947, the illustrations are a series of changing white shapes against a blue background. The reader is asked to guess what the shape is or whether it is just "spilt milk". First the shape looked like spilt milk, then a rabbit, a bird, a pig, a sheep, a birthday cake, a tree, an ice cream cone, a flower, an angel, a squirrel, a mitten, and finally a great horned owl. But it wasn't any of those 13 things. The silhouette shape makes the reader know it is a secret item until the last page. At the end of the book, the last page repeats the phrase as the first page's line. It wasn't really spilt milk but only a cloud in the sky. Then the silhouette shape becomes a real cloud in the daytime sky revealing that it was just a cloud. Then the changing white silhouette turns into a real cloud and the cloud goes up into the blue sky. The last page becomes the blue sky and the white silhouette shape which turned into a cloud. On the last page, the silhouette shape is now a real item. That is, a cloud. Then the book ends.