the river crab wears three watches

Find out why over here.

Short version. This is an image reproduced in Chinese blogs and forums in mockery at increased net censorship in the run up to both the Olympics and the 17th Party Congress. The derivation is explained at the link. The image itself is obscure enough to be unidentifiable to censors. Go ahead and reproduce it yourself, if you feel so inclined.

Relatedly, see RConversation on the "self discipline pledge" signed by Western blog providers in China.