The 'Heroes' actress slapped her hand over her mouth before giggling: "Oh my God" as the naked man ran on stage and danced up next to her.
She said to him: "Dude, what are you doing?"
He replied: "I don't know. I thought I'd do a good old streak you know. You were in that show Heroes yeah? Nice one, I'm a big fan."
Hayden responded: "Thank you. You should come grab a pint with us after."
[See also: MTV EMA 2011: Best and Worst Dressed]
The streaker finished his appearance by replying: "I would love that. Um, I don't have my phone on me though. I'll just leave you to it and I'll see you at the after show" before running off.
It was a pretty well put together skit to have been ad libbed, so we can't help but wonder if it was a set up rather than a spontaneous outburst.
Twitter erupted into a debate over whether or not it was rehearsed.
Either way, it made us giggle.
Full List of MTV EMA 2011 Winners
Best Female — Lady Gaga
Best Male — Justin Bieber
Best Pop — Justin Bieber
Best Song — Lady Gaga, 'Born This Way'
Best Rock — Linkin Park
Global Icon — Queen
Best Video — Lady Gaga, 'Born This Way'
Biggest Fans — Lady Gaga
Best Alternative — Thirty Seconds To Mars
Best Hip Hop — Eminem
Best World Stage — Thirty Seconds To Mars
Best Push — Bruno Mars
Best New — Bruno Mars
Best Live — Katy Perry
Best UK & Ireland — Adele
Best Worldwide — Bigbang