Rob's Tush a 'Secret Weapon,' Says Arquette

For years we've been hearing all about those famous Kardashian assets, but who would have guessed Kim's curves were stealing the spotlight from a more deserving candidate, her brother Rob.

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On Wednesday's Late Night with David Letterman, newly appointed Dancing with the Stars contestant David Arquette spoke to Dave about the brand new cast, in particular Robert Kardashian who he couldn't help but to compliment on his "great ass."

Arquette goes on to praise Rob's backside as "fantastic. I really think it's going to be his secret weapon."

Only time will tell if Robert's "secret weapon" will bring home the mirror ball. Sister Kim was the third contestant to get the boot in season seven.

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The Late Show with David Letterman airs weeknights on CBS.

Season 13 of Dancing with the Stars premieres September 19th.