This Day in Parody, Mash-Up and Remix: Inauguration 2013: A Bad Lip Reading:

American courts and the US Copyright Office have made it clear that, even though the author of a work hasn't given permission, it's OK to create an unpermissioned parody.

So what's a parody?

As attorney Michael Donaldson explains: "A parody is an imitation a work that comments directly on the work and therefore is allowed to take quite a bit from the work that is the subject of the comment."