Usually on a forum, when a user posts a very long block of text, with no paragraphs for separation, it is very difficult to read and looks like a "wall of text".

The full version is "China called, and they want their wall back" (Referring to The Great Wall of China), but is usually abbreviated to just "China called..."
User #1 *A very long single paragraph of text*

User #2 China called...
by Ns5.X August 16, 2010
Get the china called... mug.