69938As if Justin Bieber's vacation couldn't get any more eventful, the singer is now showing off his bare butt for the world to see! The Calvin Klein model uploaded a shot of his bum on a boat, and everyone is freaking out. Um, he's definitely putting everything out there. And his simple caption, "Look," pretty much says everything. But the rest of his trip seems like it's been pretty calm. He's been chilling in a tropical environment.And posting some introspective photos off of the aforementioned boat. Are you shocked that Justin bared all on Instagram? Can you believe that he did this? Let us know in the comments!