Answer:
Where jewelry pierces your head.
When a doctor hits you with a hammer he is testing this
What has black spots and a white face, is fat not thin, and helps you to win, but tumbles all over the place?
What travels from coast to coast without ever moving?
Power enough to smash ships and crush roofs. Yet it still must fear the sun.
Almost everyone needs it, asks for it, gives it. But almost nobody takes it.