I think this is not Mandarin Chinese. Please move it to the appropriate Chinese dialect.

It's Mandarin, although it uses the uncensored characters. You might've seen it as 操你妈逼 or similar. It literally means: "Fuck your mother's cunt."

https://en.wiktionary.org/wiki/%E8%82%8F%E4%BD%A0%E5%AA%BD

@Yorwba: you're right, it does seem to be used as the Mandarin Chinese "Fuck you". But wouldn't 肏你妈 be a better translation? It seems much more common and is included in various dictionaries, unlike the version with 屄 suffix. Or perhaps 肏你妈的屄.

As a native speaker, I'm sure that "肏你妈屄" is 100% Mandarin and it's very frequently used in everyday speech for expressing hostility. It is acceptable as much as "肏你妈" is. Many Chinese dictionaries published in China are prescriptive rather than descriptive, so they simply do not tend to include abusive words. Besides, though the character "屄" is the etymologically correct one, many native speakers prefer to use "逼" instead, just like they prefer "操" instead of "肏". All these facts may account for the lesser frequency of "肏你妈屄" in written Chinese.

PS, if you find "肏你妈屄" is less frequently used than "肏你妈", another reason lies in the fact that the former is more offensive than the latter one. In everyday life people are less likely to have such a degree of hatred.

@jiangche: thanks for your explanation! That really clears things up.

As an aside, I did ask my wife (also a native speaker) about this sentence, but she told me it wasn't correct Chinese. The fact that she is from Taiwan rather than Mainland China might have something to do with it, in addition to the fact that the most offensive Chinese swearword I've ever heard her use is 糟糕 ;-)

Hi @Rubrick! If so, perhaps Mainland Mandarin uses "屄" more often than Taiwanese Mandarin, though both varieties acknowledge "屄" as a standard character. Please see the entry in 教育部重編國語辭典修訂本:
http://dict.revised.moe.edu.tw/...d=W00000000314

现代汉语词典, published in the People's Republic of China, includes this character as well.

PS, please accept my respect for your wife's impeccable manners! :)