Say you find a profile of a friend on a dating website. They've obviously tried to obscure their identity (no face pics, didn't use their own town, etc), but you're not sure how much they realize how immediately identifiable they are. There are some details you know would possibly be embarrassing if other friends/family found out (example: they're married and looking for casual sex). Would you tell them you found them?
Have you ever found out any secrets about your friends or family from the internet?