"Address me without 'gui', My surname is Wang."
I was so confused by this before doing some research. I guess this is a response to "您贵姓?", which I now recall learning from my Chinese 1 textbook ten years ago, but never heard in real life.
This puzzled me too.
Actually, in Taiwan using 贵姓 is totally normal in offices, shops, hospitals etc. But, I gather it's more rarely used in 大陸.
A: 您贵姓? B: 免贵, 我姓王。
So, 免贵 is a bit like saying 別那麼客氣.
At least, that's how I understand it. I'm curious to know how much 免贵 is used.
Seriously, I start to find this word interesting. So I did some research.
First I've found this on the Internet:
The contributor of this page mentioned the book 《雍正剑侠图》. Which is a newspaper serial novel published between 1928-1943.
I've tried to look up 免贵 in a few online Chinese text corpora and I can't find any example before ROC. The earliest example of 免贵 is this book, which can be found in the Beijing University Text Corpus of Ancient Chinese: https://ccl.pku.edu.cn:8080/ccl_corpus/ (Even in text corpora for contemporary Chinese, 免贵 is extremely hard to find.)
So this word seems to be a neology created in ROC era / a colloquial or regional usage rediscovered in modern era, thanks to the increase of literacy?
I haven't tried the early mandarin text corpus of Academia Sinica (https://www.sinica.edu.tw/Early_Mandarin) yet. I think its link is broken, because it always redirects me to the home page of Academia Sinica.