Hi Josh,
social.contacts contains user data which requires Oauth in order to access. You can tell if a table requires Oauth if it uses the /v1/yql. Tables that use the /v1/public/yql endpoint won't require Oauth.
To use Oauth, you must first apply for a Yahoo! Application Consumer Key, which you can generate by
creating a new project. You must then traverse the
Oauth Authorization flow to obtain a valid Oauth token that you can use to make calls to social.contact.
There are
various libraries that can help you acquire an Oauth token from Yahoo! easier.
Best,
Daniel