Britney Spears: What is That Halloween Costume?

Is she a slutty pirate?  Is that actually a costume or just one of her "normal" outfits.  According to FadedYouthBlog, Britney wore this to an unplanned appearance at the Virgin Mega Store in Hollywood for the midnight release of her new album, Blackout.  Despite the screaming fans who still support her, Britney left when she couldn't find a parking space.  Now, that's not very nice!