The 50-50-90 rule: Anytime you have a 50-50 chance of getting something right, there’s a 90% probability you’ll get it wrong.
When Feynman was nearing death, he asked Danny Hillis why he was so sad. Hillis replied that he thought Feynman was going to die soon. Feynman said that this sometimes bothered him, too, adding, when you get to be as old as he was, and have told so many stories to so many people, even when he was dead he would not be completely gone.
Source: Richard Feynman – Wikipedia
I directed the ad to display to a Facebook account connected to the landline number for Alan Mislove’s office, a number Mislove has never provided to Facebook. He saw the ad within hours.
Facebook is not content to use the contact information you willingly put into your Facebook profile for advertising. It is also using contact information you handed over for security purposes and contact information you didn’t hand over at all.