A "Free Unfollow" is a term used to describe the Twitter mess of free-follow accounts that make you jump through hoops for their supposedly free, no strings attached follow, but then end up unfollowing you.
(a.k.a. "free low" or "freelow")
Friend: Bro, this egg account bio read: "Hi this is a free follow just because you're you. Don't follow me back, but follow @soandsoblahblah instead." So I went to the trouble of following @soandsoblahblah and guess what? The next thing I knew, the egg account unfollowed me.
Me: Breh, that is so lame. So you basically got a "free unfollow."