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Booty besties! Kim Kardashian isn't the only one wanting to show off her curves. Her younger sister Kendall Jenner photobombed the "Keeping Up With the Kardashians" star during a selfie at the gym on Friday.

PHOTOS: Kim's sexy post-baby bikini pics

"Barging in on Kim's booty self," the 18-year-old wrote. In the mirror snapshot, Jenner leaned into Kardashian, 33, from behind. The two both rocked tight-fitting black pants and sports bras. Jenner matched her workout gear with a gray headband, while the flash from the camera concealed Kardashian's face.

PHOTOS: Kim's post-baby body style

Days earlier, Kanye West's fiance caused a buzz when she posted a booty and cleavage-baring selfie with pal Blac Chyna. Commenters quickly slammed the reality star, accusing her of Photoshopping the bathroom pics.

PHOTOS: Kendall's bikini body

"It sucks when people make up surgery or Photoshop lies when I am so disciplined & work so hard!" the mom of 6-month-old North West tweeted in response on Jan. 10. "Just trying to motivate others & show anyone struggling with weight they can totally achieve whatever they want if they are dedicated!"


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