YouTube couldn't handle just how popular 'Gangnam Style' was, and it actually broke the internet. Take that, Kim Kardashian.
Back in 2012, Psy's super-huge-mega-massive-smash hit 'Gangnam Style' went up on YouTube and became a pretty massive hit, more or less straight away. It turned him into a global star as people around the world started learning to do that horse dance thing, and all of a sudden the video went beyond viral, getting billions of views.
However, that meant that YouTube needed to upgrade the software they use to count views on videos. In a statement on Google+, they said "We never thought a video would be watched in numbers greater than a 32-bit integer (=2,147,483,647 views), but that was before we met PSY."
If you go to watch the video on YouTube and hover over the counter, you'll see a bit of mathematical fun (no, really it is fun) that simulates what would have happened if they hadn't updated their system.
In case you're not bothered heading off to YouTube, why not add to the already massive view count by watching the video below. It's a catchy tune, to be fair.