Facebook: anyone knows how can someone set their public shares so that only one set of audience can see it?

Eg. A friend that I am not friends with on Facebook put something on her timeline set for public visibility but interestingly enough, when I discussed this post with another friend, it turns out that she sees everything else on this person's timeline except this one post that we were discussing, even though I see that it's set to public visibility. How is this possible? Thank you in advance.

Anonymous2014-04-13T14:48:32Z

Usually you can set it to who can see it but I am pretty sure if you want one person to see it who isnt one of your friends, it wont work. But otherwise you can choose who sees it.