Board Thread:Support Requests - Designing Your Wiki/@comment-7726294-20130520133548/@comment-188432-20130520170624

"A Wikia contributor" is the standard message. It should be showing up by default, unless there's some javascript working on your site to "unmask" the IP user. If you want to change the message, you'll need to do it in three locations for consistency:
 * MediaWiki:Masthead-anonymous-user
 * MediaWiki:Oasis-anon-user
 * MediaWiki:Oasis-anon-header
 * MediaWiki:User-identity-box-wikia-contributor.