Pippa Middleton's brother-in-law may be royalty, but that didn't stop the 31-year-old from comparing her famous butt to Kim Kardashian's!

In a surprising article for the political weekly, 'The Spectator,' Pippa addressed the reality star's famous derriere, which she — along with the rest of the world — saw smeared in baby oil when it appeared on the cover of 'Paper' magazine last month.

"I must say that mine — though it has enjoyed fleeting fame — is not comparable," the brunette beauty wrote, referring to the insane amount of attention her behind got after she appeared in her sister's 2011 wedding to Prince William. By the way, we disagree.