Lady GaGa On The Late Show

   Lady GaGa appeared on The Late Show with David Letterman last night to promote her album, Born This Way, which hit stores on Tuesday.   When Dave asked GaGa why she was only wearing underwear and a coat she replied,"I only liked the jacket so I decided that's all I would wear."    When he asked why she was wearing a mask, she answered,"I'm Batman."GaGa Said.   Next they got on the topic of