The poem is about a small boy who does not want to wash. He gets so dirty that all his toys, clothes and other possessions decide to magically leave him. Suddenly, from the boy's mother's bedroom appears Moydodyr—an anthropomorphic washstand. He claims to be the chief of all washstands, soap bars, and sponges. He scolds the boy and calls his soap bars and sponges to wash him. The boy tries to run away, chased by a vicious sponge. The chase is described as happening on Petrograd streets. Finally they meet another recurring character from Chukovsky's books—the Crocodile. The Crocodile swallows the sponge and becomes angry with the boy for being so dirty. Scared by the Crocodile, the boy goes back to Moydodyr and takes a bath. The poem ends with a moralistic note to children on the virtue of hygiene.
Moydodyr character became a symbol of cleanliness in Russia and is often used to advertise detergents and other products.
There is a statue of Moydodyr in Sokolniki Park, Moscow.