hoodlum

First attested in a December 1866 Daily Alta California article, which mentions "the 'Hoodlum Gang' of juvenile thieves". Several possible origins have been proposed. It may derive from a Germanic word like Swabian hudelum (“disorderly”) or Bavarian Haderlump (“ragamuffin”).
Herbert Asbury's book The Barbary Coast: An Informal History of the San Francisco Underworld (1933, A. A. Knopf, New York) says the word originated in San Francisco from a particular street gang's call to unemployed Irishmen to "huddle 'em" (to beat up Chinese migrants), after which San Francisco newspapers took to calling street gangs "hoodlums".