What does the pirate flag represent for the U.S. Navy?

What does the pirate flag represent for the U.S. Navy?

In some photos of the U.S. Navy destroyers, you can see the pirate flag hanging high on the mast. In fact, as a regular army, the U.S. Navy will not be associated with pirates, so there must be a reason for hoisting the pirate flag. That is a quirky tradition...