Commute home, Metro car relatively crowded. One end, gaggle of rowdy teenagers talking too loudly. In the middle of the car, large-ish family, clearly tourists, could young kids. At one point, older guy in the family, grandfather or uncle, says very loudly 'Will you please keep it down? You're upsetting our children?' I was closer to the family, and the kids were getting uncomfortable. This, of course, makes the teenagers talk even louder, and inspires one or two of the teenagers to angrily yell back, and a minute or so later, do it again, yelling something about 'making those kids cry.' Seriously. I have a lot of faith in humanity and all, but when someone is yelling at a kid to make them cry? Grrr.