"When I signed up I said, `I'm not a standup comedian. I'm happy to tell jokes and stuff but it's not really what I do,"' Wilson told The Associated Press on Wednesday.
"And you know, they were like, `Great, let's film some stuff and make it close to what you did when you hosted "Saturday Night Live."' That's kind of what we're aiming for - just funny comedy stuff. I assure you, I make an (idiot) of myself."
"My (butt) is actually revealed a couple of different times, so if anyone's curious about what my (butt) might look like ..." he trailed off. "I don't know why they would be. It's all for a laugh. My body being exposed is good for a great deal of laughs. They use it on `The Office' quite a bit when they need a laugh - they have me take my shirt off."
The Spirit Awards, sponsored by Film Independent, air Feb. 23 on IFC. The show will be broadcast live, uncut and without commercials. Javier Bardem, Cate Blanchett, Josh Hartnett, Forest Whitaker and Kate Beckinsale are among the celebrities expected to attend.
Wilson said the Spirit Awards are fun because they're so completely different in tone from the Academy Awards, which take place the next day.
"It's non-glitz-and-glam so the stars get to be themselves. It's on a beach in a tent in Santa Monica so it's more freewheeling. There's no time limit as to how long people can talk," he said. "It's kind of a ramshackle, crazy awards show that's really about cutting-edge cinema, and it's really for movie fans and actor fans."
The 42-year-old actor has a small role in "Juno" - which is up for four awards, including best picture - as the clerk at the convenience store where Ellen Page takes her fateful pregnancy test. He refers to the performance as his "four lines or whatever."
"(Director) Jason Reitman is a good friend so I'm happy for him that this has taken off this way. He's worked so long and so hard - it took him six years to get `Thank You for Smoking' made and now he's rollin'," Wilson said. "It's a great cast and a great group of people. I still go to the `Juno' celebration parties people throw, that's a lot of fun. I show up for the free food."
