My wife and I vacationed in Buenos Aires a few years ago for a week, and one night we were eating in a little restaurant and all of a sudden we were smack dab right in the middle of a big protest. We had noticed that there had been a lot of people walking around that evening but that had seemed kind of usual in that city anyway. All of a sudden thousands of people showed up banging big drums and chanting, yelling etc but in unison. The restaurant filled up with people yelling and shouting and the protest itself was on TV while we were there and they loved it. It was VERY entertaining for a while but we did get sick of the noise and jostling after an hour or so and left, we had to walk probably a mile from the area until we could get a taxi home, the streets everywhere were mobbed with people. They were really into it too

and I guess they are fairly common there. I forgot what it was about, something like the government had put some crooked politicians in jail and were now letting them out early. It's a beautiful city by the way, really nice antique, classic looking architecture.