In the United States, we have a joke that if a child digs too deep a hole at the beach, they will dig straight through the Earth and come out in China. In this Demonstration, drag the blue dot to any location on the map. The red dot moves to the diametrically opposite point on the globe—the location you would dig to if you went too deep.
Alas, it is not possible to "dig to China" from the United States. Instead, you would come out in the Indian Ocean. To dig to China, you would need to start in southern Chile or Argentina. Opposite ends of the Earth are known as antipodes. In addition to China/Chile, other examples are New Zealand/Spain and Ecuador/Indonesia.