I have social anxiety; my friend has social-fearlessness syndrome - we balance each other out.
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Coined as a parody of 社交恐惧症 ('social anxiety disorder'). Went viral on Bilibili and Douyin in 2021 after a video of streamer 双喜哥 confidently introducing himself to strangers. Often shortened to 社牛; the opposite is 社恐.
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牛逼 is mildly vulgar slang for 'badass / awesome'. It literally means 'cow vagina', so the phrase is jokingly crude. Online and casual speech only; never in formal writing.