From China Digital Space

翻墙 (fān qiáng): to scale the wall

The wall of course refers to the Great Firewall of China (GFW). Scaling the wall is a topic of great interest to many Chinese people; a simple Google search produced 4.9 million results. Those who scale the wall also form a sub-culture--those who have left the Chinternet and have arrived in the land of the free internet.