•an exciting article, news story, or piece of information; a sensation, bombshell · something that is funny, often in an unusual or bizarre way · a blockbuster, hit, highlight, anything exciting
20th century. Perhaps from knüllen + -er, where the verb would be used in its obsolete sense “to hit, bump” (compare Schlager), hence probably following dialectal usage or Yiddish קנעלן (kneln). Alternatively it may be a blend of Knaller + Brüller.