Kim Kardashian celebrated her 31st birthday twice this weekend! Kim carried birthday balloons into her Big Apple hotel on Friday before emerging later that night to do dinner with her husband Kris Humphries. On Saturday, the pair jetted off to Las Vegas to join Khloe Kardashian, Lamar Odom, Kris Jenner, and even Kim's former Dancing With the Stars partner Mark Ballas in Vegas to continue the festivities. During the soiree at the Cosmopolitan Hotel's Marquee nightclub, Kim was presented with a cake shaped like a white Ferrari, complete with Kim and Kris figurines inside. The couple marked their two-month wedding anniversary on the 20th, even though the E! Kardashian wedding special aired just two weeks ago. Kim is already back in LA following her party weekend, and tweeted her plans to head back to her old DWTS stomping grounds tonight to cheer on her little brother Rob Kardashian.