Fittingly, Kendall also recently posted this video of the two dancing to Rihanna and Chris Brown's hit "Cake."
This isn't the first time the 24-year-old British model and 19-year-old Kendall have gotten super-close. Aside from walking Chanel runways together, Kendall memorably straddled Cara for the eyebrow-raising cover of Love magazine last December.
The in-demand models have been busy lately, Kendall especially thanks to her Estee Lauder campaign and her new Topshop line with her younger sister, Kylie Jenner. The stylish sisters recently played a game of "Which Sister?" for Glamour.com, and not surprisingly, the two hilariously didn't agree on questions like, "Which sister takes the most selfies?" or "Who's nicer?" However, they did reveal that despite Kylie's penchant for Popeye's fried chicken and Kendall's supermodel physique, it's actually Kendall who eats the most junk food.
"I've always been good," Kylie, 17, says. "I have a kale salad and an organic juice waiting for me when I'm done."