The 'Heroes' actress was onstage ready to present the award for Best Song - which was won by Lady GaGa for 'Born This Way' - when a completely nude man appeared in front of her, who was later revealed to be Belfast-born actor David Monahan, and he insisted the stunt was not pre-planned.
He told MailOnline: "Two friends of mine work for the security company, they got me in but they didn't know I was going to storm the stage.
"I undressed in a backstage store room and considering Lady Gaga is walking about with a flying saucer on her head, not many people notice a guy with a black blanket wrapped around him."
David, 24, ran around the stage at the Odyssey Arena in Belfast, Northern Ireland, with his hands up in the air before telling Hayden he is a big fan of hers.
The 22-year-old stunner replied: "Thank you... you should come grab a pint with us after."
He then joked: "I would love that. Um, I don't have my phone on me though. You know what. I'll just leave you to it and I'll see you at the after show."