So far all the actors who have come from the set of G.I. Joe: The Rise of Cobra have not only admitted to overacting in the film, they've said it was required. Sienna Miller, who plays the Baroness, and Dennis Quaid, who plays General Hawk, said they just committed to overacting and left it at that.

Now Channing Tatum, who stars as Duke, shares details about the film's tone, including some lines spoken just for people who grew up collecting the action figures. Tatum spoke with a group of reporters on Saturday in Beverly Hills, Calif., where he was promoting the action drama Fighting. The following Q&A features edited excerpts of that interview. G.I. Joe opens Aug. 7.

What were the challenges of playing the lead in a huge Hollywood movie?

Tatum: I had no idea what I was doing. I had no clue. I had really no aspirations to go do a huge film like that, really, not yet in my career. I kind of got thrown into it. In doing so, it really opened my mind to [the fact that] it's just acting. It's a different style of acting. It's more skipping along the surface, and it is about the big explosions and stuff. You're not sitting there trying to do Shakespeare.

How do you take the work seriously when you can't take the film seriously?

Tatum: You kind of find it. It's weird, and you laugh at it. It's the only way to really do it. I don't know anyone that wasn't laughing on the set all the time on G.I. Joe. Especially, Marlon Wayans is my partner in the movie, and we laughed through the entire thing. I'm sitting there looking at a green screen like, "RIPCOOOORD! NOOOO!" Stuff like that, and you're just like, "What am I doing?" Or you're like, "You get the rockets, I'll get the nanomites. Wait a minute, what are nanomites?" I don't know what's going on, but you're just having fun with it. You just pray. Pray, pray, pray that they get a good take in all the slew of things, because you don't know what anything looks like. You can only trust your director, and that's it.

So far Sienna Miller and Dennis Quaid have talked about overacting in the film. Is that what you're referring to?

Tatum: Exactly. I was afraid of overacting, but that's what you can't be afraid of. You don't have to overact. I was the guy they'd have to pull it out of me. I'm like, "No, man, it just feels too bad. I can't do it." He's like, "Just trust me. Promise me you're going to do it, and then I promise you I won't use the take if it's not right." Then I'm like, "OK." Ugh. I do it, and it'd just be pulling teeth. You see it back now. I haven't seen the movie, but I've seen [it while doing additional dialogue recording], and it fits. You can't believe it. You thought you were just the worst actor on the planet.

What was the line you thought you'd never say with a straight face?

Tatum: Marlon, actually, it wasn't me. Marlon had a line that was like, "And a kung fu grip." Because all the Joes had a kung fu grip. He had to say that about somebody that grabbed him. He was like, "Oh, he's got a kung fu grip." I was like, "That ain't ever gonna work. That's never, ever going to be in the movie," and it's in the movie, and it works a little bit. All the fan boys will be like, "Yeah!" And anybody that doesn't know about the kung fu grip will be like, "Oh, whatever, it's just what he chose to say right then."

So it's self-referential?

Tatum: Yes, it's very, sometimes. Just for the wink at the crowd.