I get that too often, and yes, it does get annoying. Especially when you tell them what you are and they're like, "NOO , NO YOU'RE NOT HURRR HERP DERP.".
I may look mixed, even though I probably am because of my background. Dominican people are usually referred to as 'Mulatos' , which does mean Mixed.
Even though I am essentially mixed, I'd like someone to acknowledge my heritage.