Kim Kardashian, 39, proudly showed off her popular behind when she lounged out on the sand for some new pics! The Keeping Up with the Kardashians star’s SKIMS shapewear line posted a new Instagram photo (courtesy of SKIMS) that showed three versions of the beauty in a brown crop top and matching thong bikini bottoms as she soaked herself in some water on a beach while promoting the line’s product Smooth Essentials.