Fortunately we were warned by a tour guide, or we might have fallen victim to the bird dropping/pickpocket scam endemic to Buenos Aires. Walking along a major thoroughfare under some trees, we were splattered with a gray, very smelly substance. Two young people nearby appeared to have been splattered with the same “bird droppings” and put on a great act of looking up in the trees and appearing surprised. They just happened to have tissue paper and water with them, and approached us to help wipe up the mess. We kept them at a distance and yelled at them not to approach us. We had been told they would rub us down while picking our pockets. My wife even thought she saw them getting out of a cab behind us just before the incident. The substance absolutely was not from birds. Be careful and watchful; this was in a very public area in a high end neighborhood, and is being done with the obvious acquiescence of the police; it is common knowledge with the residents.