You can use it when you "Invite People to Join" OR "Suggest to friends" (which you can find below the profile image of fanpage or group)
This is a simple code which you can use in almost any web browser (I hate IE). below is the simple code which you can copy and paste it in the browser URL and hit "Enter" while in the face page.
Google Chrome Browser plugin.
Do share your comments if you have found any other tricks to do the same on facebook.