The story
From a line spoken by the Wicked Witch of the West in The Wizard of Oz to Dorothy and her dog Toto: "I'll get you, my pretty, and your little dog too!".
Etymology from Wiktionary, CC BY-SA 4.0.
and your little dog too
Today it means: A statement that not only will the person being addressed be punished but their conspirators will also. Full definition →