How users of 'Chinese Twitter' Sina Weibo are beating state censorship

If you were scrolling through Twitter and saw a post saying "someone is playing hide-and-seek again. These people can grass-mud horse," you might be more than a little mystified.

But if, say, you were Chinese, didn't think much of your government, and knew something about fooling its stringent online censors, you may well understand the coded message.

To Chinese microbloggers, "hide-and-seek" means there has been a death in police custody. And "grass-mud horse"? It suggests the perpetrators go f*** themselves.

These are just two of a number of phrases employed by users of Sina Weibo, the "Chinese Twitter", to dodge censorship filters of the authorities in a state where internet browsing is filtered and mainstream social media such as Twitter and Facebook are blocked.

Sina Weibo has more than 500 million users, over a third of the population of China. Around 198 million of these accounts are active, but these users are fettered by many common censorship practices. As well as keyword blacklists, individual users are monitored. Even though there are around 100 million posts a day, researchers found that offending items are taken down very quickly, with 30 per cent disappearing in under half an hour, and 90 per cent deleted within 24 hours.

Sina Weibo users have come up with coded phrases to share information and criticise and mock the state, explain Perry Link and Xiao Qiang in their book, Decoding the Chinese Internet: A Glossary of Political Slang.

The authors uncover, for Western readers and no doubt Beijing censors too, the meanings behind these underground internet phrases.

"Grass-mud horse" in Mandarin sounds similar to the phrase "f*** your mother", enabling users to swear in a Weibo post. When a policeman comes knocking, a Weibo user might warn that someone is "checking the water meter" as it's known that Chinese police officers often pretend they are there to check the meter.

When a user account is deleted, Chinese activists say that the account has been "river-crabbed". This word, in Mandarin, sounds like "harmonise", so its use pokes fun at the government's stated reason for censorship – to keep society "harmonious".

Dan Wallach, a professor of computer science at Rice University in Texas, says that the phrases could remain undetected in China as long as they didn't go viral. "Once a phrase or misspelling grows sufficiently in popularity, the censors crack down on it everywhere. Historical posts suddenly and quietly disappear," he says. "China has been very vigilant at being able to attach real names to online users. They only have to arrest a few people for the message to be quite clear."

Patrick Poon, a researcher on China for Amnesty International, says that many users have turned to private text messaging service WeChat instead. "For some of the activists I know, their Weibo accounts have been deleted more than 10 times. More people tend to use WeChat for private conversations on human rights and political issues now. But some activists and public intellectuals complain that even their public WeChat accounts were blocked after they have posted 'sensitive' content."

Humans are as creative about the method of communication as they are about its meaning. In South Korea, 20ft-tall helium balloons have been sent over the border to North Korea. The balloons carry DVDs, USB drives and radios for curious eyes to unpack and upload.

In war-torn Syria, a special tech support network has sprung up to help those resisting the government to stay connected. An activist group called Telecomix sends messages for protesters as tweets, as well as sharing access to dial-up internet via its own cryptic tweets.

In Europe, tech-savvy activists help other web users dodge draconian laws by setting up bridges to virtual private networks. By downloading a "Tor bridge", an encrypted version of the user is bounced outside of Turkey, allowing them access to an uncensored internet without fear of being tracked down.

It's a cat-and-mouse game, says one activist, and the mice are putting up a surprisingly good fight. So the authorities can grass-mud horse, right?