"Using the power of Social Media, I FREAKED PEOPLE OUT by making them think I knew personal information about them!" writes prankster Jack Vale.
And he's not wrong. If you want to come across as an amazing, Derren Brown-style mindreader, then simply follow Vale's lead and check out the closest recent Twitter and Instagram posts to your current location.
From people's names to what they had for dinner last night, the results really are slightly scary - and surely a warning to us all...