Template tag: URL friendly author name

Can anyone help or point me in the right direction.

<?php the_author_nicename(); ?> (made up example)

I use to have a template tag which called the author’s username in a url friendly format, but have not been able to find it. For example:

Someones Name (As the Username)

Would be inserted as…

someones-name

If any one knows the tag or can point me in the right direction it would be greatly appreciated.

Thank you for your time!