Kylie Jenner continues to heat up the winter.

The Keeping Up With the Kardashians star took to Instagram on Friday, Jan. 22 with a sultry, sun-lit photo of her and longtime friend Stassie Karanikolaou, both clad in bikinis. Kylie rocked a nude, patterned bikini while Stassie wore a tiny green and blue one-piece. Aptly captioned "that's my best friend," the photo appears to be from Kylie's recent vacation south of the border.