If Social Network star Jessie Esiennerg had turned down the coveted role of Facebook CEO Mark Zuckerberg, SNL's Andy Samberg would have been the perfect replacement!

The funny guy took over for Zuckerberg at the fourth annual Facebook f8 Developer Conference, giving the keynote address on Thursday.

"I'm going to start by focusing on key issues. First: authentic identity. And under this sweatshirt are rock solid, cut and greased abs!" Samberg teased, before going on to say Facebook put a "bullet in the back of it's [MySpace] skull… kidding, kidding… not kidding".

The actor also joked about user growth, confessing:

    "The site is growing so fast that honestly we just stopped counting you guys. We've got more people than the population of Europe, more people than in the cast of Glee, even more people that claim they came up with Facebook. Burn!"

It finally became too much for the real Zuckerberg, who appeared on stage, "Andy, what the h*** are you doing?" Before Samberg revealed, "I'm wearing a hoodie, flip flops -- classic Zuck Dog! Sometimes I want to be you Mark. I want to take your face… off."

Check out the hilarious video above!