What causes something to go viral? Studies have been conducted, and articles and books written, to try and find an answer to that question. I've read at least a few of these, and it seems that the necessary characteristics can be summed up rather easily. As Liz Rees-Jones, Katherine L. Milkman and Jonah Berger put it earlier this year in a Scientific American article:
What our findings mean for practical purposes is that if you’re trying to create content that will make a big splash, making the message positive is likely to help, and emotionality is key. Of course, more interesting, practically useful and surprising content is also more likely to go viral.The problem, however, is that this "answer" is so overly general that it's a bit disturbing to learn that two of those authors are respected researchers. What's more, those don't seem to be defining characteristics of the Gangnam Style video that garnered more than two billion hits. True, very few items succeed in going viral to that extent, but it's still significantly different from the reported 26 million people who added the rainbow background to their Facebook profile pictures. And when we consider the vast multitude of Facebook users, I suppose that a good case could be made that if 26 million users are only a bit less than 2% of all Facebook users, maybe this wasn't quite as viral as originally thought.