The Men In Black star, who will present the Nobel Peace Prize with his wife Jada Pinkett Smith at an Oslo ceremony tonight, said that he has vowed to behave himself on stage in front of winner Barack Obama.
Will told USA Today: "I'm going to have to restrain some of my standard dumbness!"
Jada added: "We want to make it seem as though we are hosting very prestigious guests in our living room. We want to be able to just bring some warmth and a little laughter and fun into the programme."
The event includes performances by Wyclef Jean, Donna Summer and Natasha Bedingfield.