How can I get a tumblr url that's taken?

[Awesome]

I really want the tumblr urls money, food, dolphins, and a lot of other urls. But they are all taken and are inactive. I can't seem to find a way to message the user. I was thinking of messaging tumblr support and pretend to be from a company or something so they can release the url. Will it work? How can I give proof? Tumblr doesn't release the url if your just a regular blogger. How can I get the url? Will anybody help me in the process?