Just clicked on one of those "who is your celebrity twin " type links which a friend has done (because I obviously don't have anything better to do 
) and it says "log in to Facebook " where you tick a box to agree. When I click on "edit" privacy it basically has all these boxes ticked for you to say they will receive your name, date of birth, email, friends lists and photos! This isn't the first time I have seen this type of agreement on these things and I end up not bothering because I don't want to share this private information with who know who. If you try and untick the boxes it doesn't let you do it.
I have seen many perfectly intelligent people do these quizzes/bit of fun type posts but find it quite shocking that they have been happy to share their private information.
Do people not realise what information they are sharing on these things or do they just click the link and not care? I find it bloody scary tbh!