From China Digital Space
天朝 (tiān cháo): Celestial Empire
The Celestial Empire is an ancient name for China. Recently, netizens have used the term sarcastically to refer to China under the current government. Oftentimes the term is used to suggest that China’s leaders are self-important and have a China-centric view of the world.
“The Celestial Empire” is also used in other sarcastic plays on words, including “The Celestial Empire goes in the pot”, 天朝上锅 (tiān cháo shàng guō), which is a close homonym for “the Celestial Empire above all other nations.”
Perhaps because the phrase is often used in criticism of the government or state of affairs in China, an alternate way of writing it has previously been blocked as a search term on Sina Weibo.
“TG” is sometimes used as an abbreviation for the phrase, but it can also stand for 土共 (tǔgòng), another name for the Communist Party of China.