Britney Spears took to Instagram to release three short video clips of her dancing in a bikini to the song “S.O.B." by Nathaniel Rateliff and The Night Sweats. While we don't think you should need any particular reason to post a video of yourself dancing (in any state of dress), Britney Spears is a pop star and so we ask WHY? Or more accurately, what is she promoting? A new album? Her Vegas show? A line of swimwear? Months of personal training? We eagerly await clarification.