The entertainment world is seen by many as an insular bubble unto itself, and Hollywood a small down where everyone knows or works with each other.
To a degree, both these assumptions have truth to them.
Yet while some celebrity friendships go way back (waaaay back) and other BFFs are well-documented, there are plenty of others you'd never expect.
Celebrities also aren't immune to fangirling/boying out.
If Jennifer Lawrence has taught us anything, it's that stars can geek out about meeting stars on red carpets, in press rooms and the like, just like we would.
Thanks to the selfie, more and more random celebrity run-ins and unlikely friendships are being documented on social media for the public to enjoy.
And, occasionally, scratch our collective heads at.
Here are 17 celeb selfies we never saw coming: