Today, I randomly was thinking about local, Hawaii, customs we have that I found differ from other parts of the US.
Here in Hawaii it is pretty standard to address older (than one's self) adults as Auntie or Uncle as a sign of respect. For example, my sister calls her boyfriend's parents Auntie and Uncle. I realize that may be a bit strange elsewhere as one would associate that referencing to my sister dating her cousin, which is not at all how it is meant. The terms Auntie and Uncle are titles given as respect that they are elders, which is expected to give respect anyway, but more so that they are endeared as one would family.
I've run into situations with mainlanders that this custom is, for lack of better words, unacceptable. My old college roommate's father wanted me to call him by his first name, Tom, instead of Uncle Tom, which I have to admit felt weird to call him that also. I felt like I was being disrespectful in bringing down my elder to my level by just using his first name, but to respect his wishes I did call him Tom. Although, I did avoid addressing him by name as much as I could by substituting in sir when necessary to get his attention.
I know this custom may seem strange to other people and I was wondering what other "strange" customs other's may have (not limited to addressing peers or elders) in their community.