Cao ni ma is a Mandarin phrase that literally translates as a vulgar insult aimed at someone's mother, and its sound-alike counterpart, the grass mud horse, became a well-known Chinese internet joke used to mock censorship and express defiance. As short clips travelled from Chinese forums and video sites to TikTok, YouTube and global meme pages, the spoken phrase itself became shorthand for blunt frustration. It remains popular because it is short, instantly recognisable to Mandarin speakers, and funny to wider audiences as an exaggerated reaction sound even without translation.