A colloquial phrase used to describe the act of superficially decorating or "dressing up" a fundamentally unchangeable or plain object, concept, or situation. It highlights that no matter how many leaves, lights, or ornaments you hang on something to alter its appearance, its core foundation remains exactly the same under the surface.
"He spent thousands putting a body kit and a massive spoiler on that broken-down commuter car, but a tree with no branches is still a stick in the mud."