Looks like Kourtney Kardashian has found the junk in the trunk that her younger sister Kim Kardashian seems to have lost!

MUST SEE: Scott Disick to Expose the Kardashians — Get the Scoop!

Kourt is currently vacationing in Miami with her three kids — Mason, 7, Penelope, 4, and Reign, 2 — as well as Hailey Baldwin (who is either babysitting the kids, or Kourt’s attempt to pull a Scott Disick by gallivanting with a woman waaay too young for her), and she managed to show her ex exactly what he’s missing by flaunting her bigger-than-ever booty while splashing around the beach with her kids!

Check out the video to see the 38-year-old’s butt!

Interestingly enough, this comes shortly after our friends at Life & Style noted that Kim’s butt appeared to be shrinking — perhaps in an effort to let Kourt dethrone her younger sis as reigning Booty Queen of Calabasas!

If there’s one thing we know for sure, it’s that these ladies love to one up each other… So we can’t wait to see what Khloé comes up with next!

Scroll through the gallery to see how much all of the Kardashian/Jenner ladies’ butts have changed since becoming famous!