It's no prank — "Punk'd" rascal Dax Shepard is becoming a legitimate movie star.

He hits the big screen next week in "Without a Paddle," has just finished a comedy with Luke Wilson and has now signed on to co-star with Tim Robbins in a big-budget adventure tale.

The latest project, called "Zathura," is based on a children's book by Chris Van Allsburg, who also wrote the story that spawned "Jumanji." Like the 1995 Robin Williams movie, "Zathura" is about a board game that sends two kids into another world, only this time it's outer space instead of the jungle.

Dax will play an astronaut who has been trapped inside the game, while Robbins plays the kids' father. "Swingers" star and "Elf" director Jon Favreau will direct when production starts later this summer in Los Angeles.

"It's gonna be a blast," Shepard said. "They built these huge sets that rock back and forth and then these tanks ... and the whole thing will go 40-degree [angles to either side] so it will be really fun to make."

Dax heads into "Zathura" coming off a comedy directed by "Beavis and Butt-head" creator Mike Judge.

"Basically, Luke Wilson gets frozen in time for 1,000 years," Dax explained of the untitled flick, at one time called "3001." "He wakes up and everyone has become stupid because all the idiots reproduced. And I'm probably the stupidest of all the stupid people and I'm Luke Wilson's lawyer and best friend. It's hilarious."

Also hilarious, according to Shepard, is "Without a Paddle," which opens Wednesday. Although the movie is mostly a comedic platform for Dax, Seth Green and Matthew Lillard, the movie also required some serious stunt work from the actors.

"We were always game for it," Shepard said. "But if you get hurt you have to shut down the entire production of the movie and 150 people have to hang out while you recuperate from a broken leg. So there were limits on what they would let us do. They wouldn't let us jump off a waterfall, for instance, or ride the four-wheeler off the cliff ... surprisingly they didn't think we were equipped to do that. But the whole four-wheeler chase scene through the woods was real, and all the canoeing."

For Dax, the highlight of the movie was meeting co-star Burt Reynolds.

"He's my biggest hero of all time," he said. "I've said this repeatedly. On 'Punk'd,' I brought up that I love Burt Reynolds in one of the bits, so my love for Burt Reynolds is no secret. 'Smokey and the Bandit' is probably the best movie ever made."

Check out everything we've got on "Without a Paddle."

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