I have a way to see hidden facebook list of friends. I shared this with someone - but I guess they don't need it anymore so I'm sharing here now.
It's easy. Use a brand new profile that has zero friends and use it to send a friend request to your target. After that - all their friends start popping up in your friends suggestions area. You can X them out until you exhaust the list.
Have fun GuGers!
To protect yourself from this - well you really can't until the loophole closes.