Assuming I am Hispanic ticks me off

Once I sat next to a lady who kept on code-switching between English and Spanish with me. Why again did she think I could speak Spanish? People just assume I can speak Spanish. It drives me crazy. This other day I was at the train station and this lady looks at me and asks me IN SPANISH what time is the next train to NYC! 

:/

I just shrugged. 

Honestly, why should I understand what you're saying? If you had assumed I could speak Portuguese and spoke Portuguese with me I'd be fine. 

NOT SPANISH!!!!!

Then another day I was at Walmart, wearing a BRAZILIAN flag shirt. On my way out this black guy looks at my shirt and goes - Buenos Dias!

Oh, please, no! Look at my flag! Look at my flag! Please! No Spanish! 

I looked at him as if I had not the slightest clue of what he said, and kept walking. From a distance I could hear him yell, " Buenos Dias!"

Argh!!!!!