When celebrities and ‘normal people’ meet the exchange is usually the same – an awkward request for an autograph or a photo, an awkward obligation. Or, if you’re a normal person and you’re part of a baying mob of normal people, lots of balshy shouting and screaming at the celebrity whilst they flee for the cover of their limbo surrounded by security. How nice then that 67 year-old Ellen Grossman managed to strike up a completely cordial and comfortable conversation with rap superstar Jay Z – because she didn’t know who he was.

A Youtube documentary shows Hova getting on the subway on his way to the last of eight performances he was giving at the Barclays Center in Brooklyn. An excellent publicity stunt, his arrival onto the train was followed by hundreds of others, screaming and holding their phones up to record this momentous moment. However, as he sat next to Grossman he was asked “are you famous?” It took Jigga by surprise and he replied “yes. Not very famous, you don’t know me.” A sweet conversation followed before the pin finally dropped as Jay Z finally gave his full stage name to her.

Talking to The Guardian, Grossman said "My first thought was oh my God there's been a disaster upstairs," she said, before saying that she also thought it might’ve been a flash mob: "They were all taking pictures of a man I did not recognize." However, eventually it clicked and she enjoyed a 20 minutes conversation with the rapper as he made his way to his stop. "It was just a wonderful conversation” she enthused. “He's very real. He didn't seem disturbed that I didn't understand who he was, he's not full of himself."

Watch Jay Z's Barcalys Center Documentary