office boy

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A boy or young man employed in a business office to do odd jobs and errands.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A boy or junior clerk employed in a professional office to perform odd jobs, such as running errands or making copies.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a young man who is employed to do odd jobs in a business office