Fake news, people that think it's real news, and people that want people to know that there are people who thought the fake news was real news.
On the 18th, The Onion ran an article detailing a new $8 billion Planned Parenthood facility called "The Abortionplex". In typical Onion fashion, the article was gleefully tongue-in-cheek, timely, and completely, utterly false. The Onion is, of course, a satire news site.
That doesn't necessarily stop people from believing it. This wouldn't be the first time that the masses have bought an Onion line. Nor would it be the most ridiculous thing the general populace has believed. That being said, this graphic (click through) shouldn't come as a surprise to anyone—and yet it's one of the most interesting internet artifacts I've seen, as there is no attempt at all to prove that it is authentic.
I want to be sure that I go one record saying that I don't have any doubts as to the legitimacy of the graphic. However, if someone wanted to create a false graphic on this or any other theme, the ubiquity of Facebook thumbnails and Photoshop makes it possible for them to get involved in made-up guerrilla journalism. The Culture Wars no longer require facts (but they do need the lulz).
Eli Pariser notes the advent of the "filter bubble": the way that Google, Facebook, et al. filter content that you receive based on previously expressed preferences. His TED Talk approaches the most obvious problem with the filter bubble, which is that as websites tailor content automatically, people aren't exposed to opposing viewpoints. There's another angle here, which is that these filter bubbles protect false ideas from being debunked except by untrusted "outsiders". It's clear that the Obama Kenyan birth certificate is a fake, that vaccines do not cause autism, and that the Bush administration did not conspire to cause 9/11, but these ideas continue to spread.
Consider this: we are creating a world in which large social groups not only have different views as to how the world works, but can actively produce proof that their worldview is correct. Worse than that, the low barrier-to-forgery makes it easier and easier for us to disregard facts we find inconvenient to our preconceptions.