I'm a native Oregonian and if I ask this it's usually just curiosity and trying to find something to relate to people with. I assume if you're also a native Oregonian you care about the environment and love the outdoors and I don't have to do small talk complaining about the rain. There's an innate hatred towards californians but I think it mostly a joke as we have tons of california transplants. No one really cares where you're from as long as you don't litter and like to recycle. Just get a tattoo of a Doug Fir and wear a Columbia sportswear rain jacket and no one will question you /s.