"Smooth brain" is a slang term used to describe a person considered unintelligent, dull, or lacking common sense. It comes from the idea that the brain's folds (gyri and sulci) are associated with intelligence, so a "smooth" brain implies a lack of mental complexity. The term emerged in online and meme culture in the 2010s, often humorously or mockingly to highlight mistakes, naivety, or ignorance. It is mildly to moderately derogatory, mostly playful or teasing, and is used in informal, digital, or social contexts rather than as a deeply serious insult.

What is the origin of the term "smooth brain" and how is it used?

英語での「smooth brain」の定義と意味

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