The U.S. Equal Employment Opportunity Commission (EEOC) has cited the phrase as indicative of national origin discrimination. Specifically, in a brochure titled “Employment Rights of Immigrants Under Federal Anti-Discrimination Laws“, the EEOC states (under the heading “Harassment Based on National Origin”):
Ethnic slurs or other verbal or physical conduct because of national origin are illegal if they are severe or pervasive and create an intimidating, hostile, or offensive working environment, interfere with work performance, or negatively affect job opportunities. Examples of potentially unlawful conduct include insults, taunting, or ethnic epithets, such as making fun of a person’s accent or comments like, “Go back to where you came from,” whether made by supervisors or by co-workers.
While all of the evidence must be considered, the use of the phrase may suggest unlawful discrimination / hostile work environment based on national origin.