used as a substitute for 肏你媽|肏你妈[cao4 ni3 ma1], to mock or avoid censorship on the Internet
Definitions (Wiktionary)
intj, Mandarin, euphemistic
fuck your mother
noun, Mandarin, slang
frustration; anger
我心中有千萬只草泥馬在奔騰。
我心中有千万只草泥马在奔腾。
wǒ xīn zhōng yǒu qiān wàn zhī cǎo ní mǎ zài bēn téng . I am deeply frustrated. (literally "In my heart there are many Caonima galloping")