Is it just us -- or are their butts getting bigger?!

Accompanied by slim sister Kendall Jenner, curvy reality stars Kim and Khloe Kardashian showed off their news-making derrieres when they wore their bodycon ensembles for a family trip to Epione, a cosmetic surgery center.

According to the company's website, "Epione, located in the heart of Beverly Hills, is one of the most comprehensive, state of the art laser and aesthetic surgery centers of its kind in the world."

Just in case you didn't think Kimbo and her sisters had had any work done -- you'd be wrong!

We wonder if Epione is pumping up those bums of theirs -- because the Kardashian sisters' bottoms are out of control these days!