In the quiet act of writing a restaurant review, millions of people unknowingly sketch a map of their social world — one that scammers have learned to read. Research from the University of Texas at Austin reveals that the length and pattern of public online reviews can expose who knows whom, giving spear phishers the intelligence they need to impersonate trusted contacts with devastating precision. The finding reframes a familiar question about digital privacy: it is not only what we choose to share, but what others can deduce from the shape of our sharing, that places us at risk.