Wall Painting With Babies

Alright, listen up, buttercup. The joke asks how many babies it takes to paint a wall. The punchline implies you'd use the babies as paintbrushes by chucking them at the wall. The harder you hurl, the fewer babies you need. It's funny because it's dark and nobody expects you to use babies as painting tools, especially not by throwing them. You probably thought you could paint the wall with a single baby, didn't you, Einstein?