Some people on Facebook may opt to hide their friends list from you. WonderHowTo shares some tricks on revealing those "private" lists.
Once you have your target picked out, the process is pretty simple. Follow these steps to start uncovering their friends:
To start, you'll need to do a little detective work. Identify a probable friend of your intended target. Think of where your target works, groups they could be members of, and people they might associate themselves with. If you don't anything to go on, use Facebook's Graph Search feature to find potential friends.
Once you've nailed down a friend of your target, you need to find out both of their account ID names. You can find these by going to their Facebook page and looking at the end of the URL. It will read
https://www.facebook.com/ACCOUNT_ID.
With both user's IDs, insert them into a URL that looks like this:https://www.facebook.com/TARGET_ID/friends?and=FRIEND_OF_TARGET_IDWith that search, you'll see every friend that they have in common. From there, it's a process of elimination until you uncover all of your target's friends. If they have 300 friends and your search came up with 50 friends in common, you know there are still 250 friends to identify. Repeat the process to reveal them all, but it should be easier once you've discovered the first round of Facebook friends.
Chances are you don't need to see their whole friends list, but if you do, there's also a script that'll automate the process for you at the link below. This logical approach to uncovering hidden friends doesn't break any rules and is easy to do if you have a little time.
How to Hack Someone's "Private" Friends List on Facebook to See All of Their Friends | WonderHowTo