With US citizens
Crossing the border to get a view from the Brazilian side is normally no big deal: you line up at the immigration, get a stamp and move on. But since all the children, Anna, Helene and Raphael as well as Rebecca were traveling with their US passport, this excursion turned into an expensive challenge.
In the aftermath of 9/11, the US government requested visas for Brazilians entering the US, so President Lula retaliated by making it a requirement for US citizens entering Brazil.
Now paying USA 150 for spending one afternoon in Brazil seems a bit dear, so most nationals requiring a visa enter Brazil illegally. Somehow the taxi drivers have worked out a system with immigration officers at the border and obviously the system works well. But Joel & Rebecca decided against it and bought a regular visa, which made this a very expensive day and had them line up exactly eight times that day! We kept teasing them about not loosing their golden passports.