Fifties fun with Kylie and Kendall Jenner!

Kim Kardashian's younger siblings had a bit of fun poolside Saturday, and posted pics on Instagram to prove it.

In the glam shots, model Kendall, 16, shows off her fit figure in a red and white checked top and striped skirt, while her sister Kylie, 14, gave a kiss to the camera wearing a floral bustier and miniskirt.

Kris and Bruce Jenner's daughters also goofed off, posing for a series of photos that displayed their best 'duck faces.'

Appointed as West Coast fashion contributors to Seventeen, the Jenner sisters will soon debut their own column, Kendall & Kylie's Fashion Journal, in the June/July issue.

"People always ask us for fashion and beauty tips, and now we can share them directly with readers. It's really exciting for us!" Kendall wrote on their official website.

A model for Forever 21 and Nordstrom, Kendall and her sister will premiere the seventh season of the family's E! series Keeping Up With the Kardashians May 20.