Person is mistaken for an ethnicity not their own
Is This Tropeable? A character or actor is assumed by another to be of a particular ethnicity when they're in fact not. Common enough experience in Real Life for those whose features conform to a stereotype or who live and/or work in a particular area or profession. The character/person's reaction to the assumption can quickly give an insight into their attitudes. Specifically not overlapping with Mistaken Nationality, as nationality is not, in the case of this trope, the issue, but rather the person's background. Potentially Unfortunate Implications - "You look (insert ethnicity)". Usually (but not always) white people being assumed to be Jewish/Hispanic/black.