FQL: Fetch friends of a friend

How could I fetch the friends of a friend of mine with FQL or something other of the FB-APIs? At the normal website of开发者_开发知识库 Facebook it's possible to see the friends of a friend of mine if I visit his profile and add ?sk=friends to the url.

According to the FQL docs on the friends table

the friends of friends cannot be retrieved.

When you try to access a friend's friends you'll get this message:

"Can only lookup for the logged in user 
or the logged in user's friends 
that are users of your app."

So you can only retrieve a friend's friends who have authorized your app.

Friends of friend can access only when one friend of your friend, your friend and you (loged user) use same app and give permission to access there data.