It was the last day on Earth (Dec. 20th, 2012) and Marilyn Manson was performing live in Kyiv, Ukraine. So he simply had to sing this song, while he never did in other cities during this tour. That was great! (Sorry for the video quality) :)
In fact, The Last Day on Earth has only been performed live twice: first time in Las Vegas, Nevada on December 31st, 1998 and second time in Kyiv, Ukraine on December 20th, 2012.