I speak spanish natively and at during uni I would hang out with a group of Brazillian friends. I would speak a mixture of portuguese and spanish with them.

The mom of one of these friends made a Brazilian dish for us (Feijoada) and asked me how it was as it was the first time I tried it. I answered that the dish as 'exquisito', which in Spanish means delicious (similar 'exquisite'). She seemed somewhat disappointed and upset by my response so I probed a little and found out that 'esquisito' in Portuguese actually means 'weird'. She thought I was calling her dish weird tasting. I found quickly enough to clarify, but I did feel bad about making her fell that way... She was very excited about sharing her cooking and she thought I called it weird.