Word to my mother comes from New York City slang, especially AAVE, where word to my mother or word to my dead is a serious oath meaning you are telling the truth. The clipped version spread on TikTok and in meme edits as a reaction sound, shortened for quick cuts and captions. Its popularity comes from how instantly recognizable the phrase is even out of context. Creators reuse it as shorthand for I swear I am not lying, which works for jokes, stories, and arguments.