Adjective getting or exhibiting a very abnormal or Unwell state of brain See 245 synonyms and more non placet As an interjection to negate what was explained ahead of or reveal it as sarcasm, it is attested by 1900, popularized 1989 by "Wayne's Environment" sketches on "Saturday Night time Stay" https://non79124.tokka-blog.com/27175950/the-taschen-diaries