I think more people are in on the joke than Ali G and Borat let on. The controversial clip with Borat in the country bar singing "Throw the Jew Down the Well" happened in Tucson, AZ. When an investigator for the Jewish Defamation League [sic - DH] called the bar to talk to the owner about the incident, he ended up speaking with the bar manager who was working that night. The bar manager is Jewish and basically said, "We all thought it was hilarious. This guy with an obviously fake moustache came into the bar and starts telling jokes in a ridiculous accent. It was like some impromptu comedy routine. Everyone was singing along with the song because we knew it was a joke." Sure, many people are really duped by Cohen, and that's what's really funny. And that's also what the film makers cut the movie around. That dawning, "this is a joke reaction" isn't shown to the viewing audience.