One of Lily Allen's best-known songs is called "Smile."

Well, the British pop wreck recently gave celebrity hairstyle watchers a lot to smile about when she upgraded her raggedy-ass pink 'do for the healthier and cleaner, chestnut-brown cut seen below (in London on Monday).

Before that, Allen had gone from pink to blonde, then back again!

Just two of the many hairstyles of Lily Allen.

You know what they say. Nothing makes a pop singer look new, reinvented and 100 percent stable like a new blonde weave! That or a conservatorship.