Well, as we say in Brazil, opinions are like assholes: to each their own.
we have the same saying in Poland
We have the same saying in my household :p
... hasn't anyone here watched Dirty Harry? It basically globalized the saying (Opinions are like assholes, everyone has one). That being said it doesn't have any sort of "secret" meaning that only works in certain languages so there's really no reason why it'd be some language specific thing in the first place ^^;
Oh, I had no idea it was a movie quote. I guess that was probably where it came from.
It's not just a movie quote. It's been around for a long time.