I get a bit annoyed when I am gming a game, and I spend lots of time developing and creating a setting, and someone just posts a character with a backstory including an entirely different region or culture that their character is from that I didn't have in my setting. I know that role playing is collaborative and everything and I think it's great that they want to create a unique character, but It annoys me more that they didn't even run it by me first. It just feels so presumptuous and entitled to me that someone thinks they can walk in and insert something into my world then expect me to just accept it and their character. The disappointing thing for me is that usually I like their ideas too, and I would be happy to include them if they ran them by me via pm, and we could develop how it actually fit into my setting together instead of just throwing it in.