"I immediately changed my DOB on facebook"
Hmmm, I wonder what Facebook does when someone changes something like their DOB? Or name/address/email/phone? Or any other marketing-useful data in your profile?
If _I_ were part of the Facebook Evil-Data-Mining Division, I'd certainly be looking to see if I can discern patterns like "This phillmv guy's _real_ birthday is 12/03/1975, but when he changes it for sites he doesn't trust he tends to use either 1st April 1980, or 22nd Sept (which is his girlfriends birthday) instead. And he usually changes his zipcode to the one his parents used to live at before they moved to Pittsburg."