I've never done anything completely authentic brazillian or samba, but I've never been asked to. I'm sure I could come up with something decent. Here's the closest I've probably ever done to samba:
https://dl.dropboxusercontent.com/u/21085553/Freaky%20Thang.mp3
https://dl.dropboxusercontent.com/u/21085553/Freaky%20Thang.mp3
I like it, but there is something missing there, it kinda reminded me of a James Bond back drop sound
could you try an upbeat smooth samba?