A copy boy is a typically young and junior worker on a newspaper.
The job involves taking typed stories from one section of a newspaper to another.
Reporters typed their stories on slips of butcher's paper...then a copy boy ran the story into the neighbouring subs' room, hence the cry of 'copy'. Each slip of the story had about six carbon copies...stapled together and it was the job of the copy boy - or girl - to separate the original and run it to the subs, and then separate the carbons for distribution. (from Guthrie, 2010).