Nothing like some good ol' sibling rivalry!

Brandon Jenner posted one hilarious video to his Instagram account on Wednesday, poking fun at step-sister Kim Kardashian's sexy pool video, which she shared earlier that day. 

Flipping his hair like a mermaid with some tasteful '80s porn melodies playing in the background, we gotta say, Jenner's video is pretty great.  

The 31-year-old captioned the hilarious clip, "We all know who's the hottest @Kimkardashian."  Check out Brandon's sexy moves in the video above!

Earlier on Wednesday, Kim posted one super sexy, yet random, clip of her swimming in a pool in slow motion and teased that there was more to come. Check out Kim's video below! 

The "Keeping Up with the Kardashians" stars have been vacationing in Thailand all week and it definitely looks like they've been having some fun! 

But, if we had to pick which sibling wins this hair flip off, it's Brandon!

Which video do you prefer? Tell toofab in the comment section below and click "Launch Gallery" above to see more pictures from the family's Thailand trip!

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