Your news, should you choose to believe it, came in from unnamed "dependable sources:"
"On the morning of February 10th at 2:45 pm, unknown persons broke into the residence of the highest leader North Korea Kim Jong En and shot him dead."
Suspicious traffic patterns had been seen outside of the North Korean embassy in Beijing, and this explanation, it appears, seems as good as any: Users of China's Sina Weibo, the local Twitter clone, forwarded the message more than 10,000 times. One user posted a picture of what Kim Jong Un would look like arrested. Another commented "in this weird country, that's not even strange."
The chained Chinese media universe means that Weibo rumors are a lot more trusted than their Twitter counterparts. Chinese media coverage of sensitive subjects is often deliberately obfuscating, and Chinese viewers know it. A few days ago, Wang Lijun, one of China's best known gangbusters and the right-hand man of powerful politician Bo Xilai appeared to try to defect at the U.S. Consulate in Chengdu. While official Chinese media covered the defection, they mostly copied the official Xinhua report, which failed to mention the most important point: how it affects Bo's chances of promotion.
Chinese official media reporting on North Korea is often further removed from reality than the way China reports on its own political process. (My favorite English-language example is a Xinhua article that compares nightlife in Pyongyang with New York and Tokyo.) Besides, North Korea itself is a black box: Even the best American articles often depend on rumors and hearsay to cobble together a portrait of the closed country.
All these factors combine to give the Sina Weibo rumor -- started, it appears, by a random user with less than 200 followers -- enough traction in China to land on this side of the world wide web and into the pages of Forbes, MSNBC, and Huffington Post.
It is possible that this Weibo user broke the story of a successful coup in North Korea, though it's extremely unlikely. My favorite explanation on the Twitter side of things comes from Shaun Walker, the Moscow correspondent for the Independent, who wrote "Possible that someone said he 'murdered an enormous family-sized bucket of fried chicken,' and something got lost in translation."