Let your hair down, girl!

Here's Britney busting some moves at her Piece of Me Las Vegas show at Planet Hollywood last Friday. She was werking so hard, her hair was like, "Go on without me," and just laid down on the floor for a rest.

Ms. Spears is a professional, so she just kept dancing, but you better believe that hair got REAMED after the show. Those extensions will never work in this town again!

Sources: UpRoxx