Thought to be of Chinese origin, the yo-yo has honed the hand-eye coordination of children the world over for thousands of years. And though the myth that Filipino warriors used it as a weapon has been debunked, a yo-yo would still probably serve you better in a battle to the death than, say, a Wii. This afternoon, modern-day masters of "around the world," "dizzy babies," and "worm holes" ("walking the dog" is for bed-wetters) convene at South Street Seaport to push the boundaries of the sport. A full day of yo-yo can be a bit draining, so DJs, breakdancers, "Japanese action-punk" band Peelander-Z, and a slew of other performers also take the stage.