People paid by the Chinese communist regime to comment on posts about China and the Chinese people that promote the Communist party line. In Chinese: 五毛. The term actually means 50 cents.
Example usage: "I posted my video blog to YouTube and the Wu Mao's came out with huge hate comments."
https://www.globaltimes.cn/content/1187775.shtml
Question no more...
The comments are priceless.