If you don’t want certain friends to see specific wall posts on Facebook, you can block it from their view either while you are posting or from the Privacy Settings.
While you post
1. Type your message, then click on the lock below the text box.
2. Select Customize.
3. In the Hide this from area, type a name in the These people box, then select them from the list. If you want to block all future wall posts from the friends you have listed, check the Make this my default setting box. Select Save setting when you’re done.
From Privacy Settings
1. Click Account in the upper-right corner and select Privacy Settings.
2. Select the Customize settings link.
3. From the Posts by me area, choose Customize.
4. In the Hide this from area, type a name in the These people box, then select them from the list. Select Save setting when you’re done.
Keep in mind that if you say something too dramatic on Facebook, it may eventually get around to people you’ve blocked. This feature should probably only be used in cases when you prefer certain people not to see your posts, but won’t be the end of the world if they happen to.