Большой китайско-русский словарь
shaìhēi zú
Literally “those who expose injustice.” It refers to people on the Chinese mainland who use the Internet to help expose or publicize injustice: for example by mass blogging about an incident on many different Web servers in order to overcome possible online censorship. Every Web host seems to have different censoring criteria, and thus something that gets blocked or deleted on one host server may not get censored on another.