Why people do downvote this? I mean i haven't studied ever any chinese languages or anything, but this word is interesting. The Etymology in wiktionary:
Sino-Vietnamese word from 非, as in 非洲. Also seen as a shortening of Phi châu or châu Phi (“Africa”).
You can see from wordgeek416 post how the words are flipped. I guess that i caused by the grammar rules of both languages
You can see that the pronunciation differs respectively only a little, comparing how distant languages they are