Nat Wolff had never heard of Cara Delevingne before they met on the set of 'Paper Towns'

The 20-year-old actor was first introduced to the 22-year-old star while working on the film - in which they both have leading roles - but Nat confessed their first day was a bit awkward because he had no idea who the British supermodel was.

Nat said: ''It's hilarious because when she walked in on the first day and, I think I was the only person who didn't know who she was. I really had never heard of her!''

And it wasn't until he saw the Burberry model's face on a giant advertisement near his New York home that he realised just how famous she was.

He quipped: ''After a little while, I was like, 'Oh wait, you're on a billboard with Kate Moss outside my apartment in New York. I walk my dog past your face every day!' After that, it was super chilled. She just took her shoes off and started being Margo (Cara's character).''

Thankfully, Cara didn't take the snub to heart and Nat - who plays Margo's admirer Quentin Jacobsen in the blockbuster - immediately discovered the fun-loving actress' wild side.

He told We Love Pop magazine: ''I remember this one time, we were shooting a scene outside and it was a really emotional one where she was staring into my eyes. Suddenly she just yelled, 'Is that a water slide?!' She ran off and got us all tickets to this nearby water park, it shows you exactly how spontaneous she is. She's a total goof ball.''