"哇塞" has been in use in Taiwan since 1970s. It was an expression popular among my dad's generation. Nowadays although I would still hear it once in a while. It seems the usage has gradually faded out over the years. I've been in Mainland for last a couple of years. Because I have never heard the mainlanders use it, so my assumption is that this expression is rarely used nowadays. I agree with naomi, "暈“ is a much more current and popular (although colloquial) alternative you can use in stead of "哇塞". "哇, 這麼無禮“ is acceptable in texting too. http://www.baike.com/wiki/哇塞

Hi Beth,firstly,"哇塞"is not only used in Taiwan,but also used in main three citys-Xiamen,Quanzhou,and Zhangzhou,we call these three citys Minnan Zone,where in the southeast of China-Fujian province."哇塞"is a saying just like "F*ck" in English ,so it's a derogatory term;secondly, I think in your dary "Wow, so rude"here is right,it's acceptable,but wrong used "哇塞".

I'm a mainland Chinese, we use both. Trust me, nothing's wrong with it. Many people don't actually say it out, but that's only because they think it's being a little dramatic to say it or something. I barely say it, but I don't find it wrong or unusual if I heard someone say it. I do use them once in a while over the Internet though.

I don't think so. It's just because the person is not used to using 哇 lol. But attention that your tones are supposed to be different when you use 哇 to express something good for you and something bad for you.

哇 and 哇塞 are usually used to show amazement and surprise.