Isabel Hilton writes on the Guardian:
The news that the US president, Barack Obama, had called for an end to internet censorship at a meeting with students in Shanghai lasted 27 minutes on the front page of the Chinese portal NetEase before being deleted, according to China Digital Times. But it didn’t stop the news spreading like wildfire across Chinese cyberspace.
… Obama’s visit itself became another excuse for official censorship: according to Chinese tweets, the authorities ordered all internet sites to exercise strict control of content, eliminating references to public letters to the president, meeting with dissidents (many of whom have, in any event, been detained in advance) offline protests and attacks on the Chinese government in vague and disguised language. As one Chinese tweeter responded, in an example of the kind of disguised language that enrages the censors, “f**k the river crabs“.
The river crab is a pun, one of many with which rebellious Chinese netizens taunt the censors. The word for river crab is a homonym for the word for “harmony”, a reference to the government policy of building a “harmonious society”. When a blog is shut down in China, netizens describe it as being “harmonised” and pictures of river crabs abound on the Chinese web.