Coco vs. Kim K The World's Biggest Ass-Off!

7/12/2010 2:30 PM PDT
It's an ass competition for the ages -- the curvacious Coco versus the badonkalicious Kim Kardashian. Four cheeks have entered ... but only two will emerge victorious!!!

Both ladies flaunted their famously plump backsides at the AMP Energy Bullrun Rally in New York City this weekend.

Question is ...