What does 'duang' mean in 'online Chinese'? I see this word popping up on Weibo and Taobao. It's not written with any character, but spelled out in Pinyin. What does it mean?

EDIT:

For the annals:
http://www.hollywoodreporter.com/news/duang-how-jackie-chan-helped-780040

Citation, with explanation of the word in bold:


  Think that your hair is looking particularly good today? In Chinese
  popular culture, it's looking "duang."
  
  A Chinese phrase that came out of nowhere, "duang" has taken the
  Internet by storm, even though many don't really know its origins.
  
  We do know where "duang" started though. It was Hong Kong action star
  Jackie Chan, who in 2004 was featured in a shampoo infomercial, where
  he spread his hands and described how his sleek dark locks would
  simply "duang" after a scrub with Bawang organic shampoo. A useful
  way of translating the word is as "boing," in the sense of "bouncy and
  vibrant," or even "ta-da!"
  
  A parody video making fun of the old commercial recently hit the web,
  making the word a social media trend. It's been widely interpreted as
  "cool," and the word resurfaced again recently after Chan posted it on
  his Weibo page. It has become to Chinese slang what Kim Kardashian's
  rear end is to U.S. popular culture. It's breaking the Internet as
  Chinese pop stars are called "duang pretty" and the like.
  
  Although it's a long way from featuring in a dictionary, it's been
  used millions of times on the Chinese social network Weibo and has
  been looked up 1.5 million times on China's biggest search engine,
  Baidu.
  
  In case you're "duang confused," you just need to know that
  "everyone's "duang-ing" and it's great" or "This is so duang hot" are
  the kinds of comments you see on the Weibo social network these days.
  
  There have also been numerous mash-up videos, and apparently during
  the visit of Britain's Prince William to China last week, he was
  greeted by some people saying "duang, duang," because the English
  gentry look is seen as cool in China.