Time to test your knowledge of Kylie Jenner's best friends ... so go coconuts and guess the bikini babe holding this coconut on a tropical vacation.

The hottie in the photo is BFFs with Kylie and she's also got a couple kids with her husband, former NBA baller Troy Daniels.

That's all the hints from us ... so click the gallery and find out who this babe is!!!

She's on vacation in Thailand, a country that's a popular vacation destination for lots of babes ... and we've got the photos to prove it.

Enjoy the hot shots ... and happy Friday!!!