The way you say Hi! in Portuguese is Oi! This sounds exactly like Oy!, which is Yiddish and is an exclamation of exasperation or dismay. An expression that I use frequently, and it took a while not to think Crap! every time someone said hi to me or vice versa. I'm saying it, and hearing it, more as it should be in the Brazilian context now.
Another thing that sounded funny is their equivalent to Bye bye! Their Bye! is Tchau! (pronounced as Ciao! in Italian), and their Bye bye! is, logically, Tchau tchau! This sounded so hysterical to me and Andy and Sam the first time we heard it, that we busted a gut laughing right then and there. Not the politest thing to do when someone is merely trying to tell you bye, but it couldn't be helped. We're pretty much used to that now, too.
Little by little it's getting easier for me to communicate, both because I'm learning more of the language, but I think I'm also honing non-verbal skills. I think the fellows that work in our building relish when something needs to be communicated. Actually, I do, too! It's like a game - like Charades. We employ hand motions, sound effects, facial expressions, and by the end when we've successfully relayed our message, we've won! We've hit the jackpot! It's very satisfying.