facebook: how do change the privacy setting for ONE post made by a friend?

[Celeste]

unfortunately my parents added me on facebook, and there is just one post a friend made on my wall that I want to change it so my parents cant see.
I know how to do it for ALL the posts in the privacy settings, but is there a way to hide only one post that a friend has posted on my wall?
it would be a great help (:
yes it kind of needs to be seen by other people, because it involves a few of my friends and I cant delete it because that would be mean.
its not inappropriate AT ALL, by the way, I just not something I want my parents to know about, and I know for a fact that they look at my page regularly.