Printer's devil
A printer's devil was a young apprentice in a printing establishment who performed a number of tasks, such as mixing tubs of ink and fetching type. Writers including Benjamin Franklin, Walt Whitman, Ambrose Bierce, Bret Harte, Sherwood Anderson, and Mark Twain served as printer's devils in their youth along with indentured servants.
There are religious, literary, and linguistic hypotheses for the etymology. Printers blamed the mischievous devil Titivillus or confused a name with the legend Faust. Other theories include racism, Gallicisms, or misspellings.