Nyo

I'm not too sure about that.  It's also used as an expression of mock shock or horror, something like: Nnnnnnnnnnnnnyyyyyyyyyyyorrrrrrrrrrrrrrrr.  Also, people who watch Anime use it.  Normal people probably don't, although might pick it up from people who watch Anime.  If, for example, you saw a "panty-shot" of a Nekobus, it would probably be an appropriate exclaimation.  --AR

Google seems to confirm that it is a miaow sound, although I've never heard a real cat make a noise that sounds anything like "nyo"!  Erm, also it is a useful exclamation if you want to say: "The stream of urine has gotten small" or "I have trouble making water" in Japanese: "Nyo no de ga hosoku narimashita." or "Nyo ga denikui.", although I should imagine that "Nyo" alone ought to be enough.  --AR

You've probably never heard them go 'Ron ron ron' either.  I guess that each language transliterates animal sounds very differently.  --Vitenka

Indeed.  That probably negates some linguistic theories of onomatopaeias, but I don't know enough about that to comment further. --AR

Well, rememebr that each language has its own sounds to give to the latin alphabet.  'Purr' probably isn't something you can pronounce in french without it sounding more like 'pear'.  --Vitenka