From China Digital Space
河蟹 (héxiè): river crab
Troublesome creature whose name echoes “harmony” (和谐 héxié); euphemism for censorship. Coined by netizens as a reference to the government's justification of censorship as an essential ingredient in constructing former president Hu Jintao’s “harmonious society.” As pre-Internet colloquialism, a crab is also a bully.
Both “harmony” and “river crab” can be used as verbs. Instead of saying something has been censored, one might say it has been “harmonized” (被和谐 bèi héxié) or “river-crabbed” (被河蟹了 bèi héxiè).