For some reason the guys downstairs insist upon conducting all their cell phone conversations outside their apartment rather than inside where decent Americans conduct their private business. And if you're outside for any length of time, you'll occasionally catch one or the other of them furtively glaring at you as though you're intruding.
At least they speak in a normal tone of voice. We used to have a guy across the way, a salesman, who would pace up and down the parking lot barking orders over the phone while wearing a coat and tie. It was the strangest thing; sometimes he'd be out there for hours. And you could hear every detail of every transaction.