‘Jackass 3D’ pulls no punches

Johnny Knoxville didn’t sleep very well while filming “Jackass 3D.” Few members of the cast and crew did.

They were too paranoid – a result of the constant pranks on the set – and were forced to sleep with one eye open, so to speak.

“You don’t sleep,” said Knoxville, while promoting the sequel with director Jeff Tremaine. “You check around corners and look over your shoulders constantly.

“We were like World War II fighter pilots – never let anyone on your tail.”

Tremaine directed the first two “Jackass” films, which combined made more than $164 million at the worldwide box office.

He said the third film, which opens in theaters today, left the cast and crew a little rattled.

“For the next three years, we’ll all be covering our (privates),” Tremaine said. “We’re so paranoid right now.”

What exactly did they do to each other?

Tremaine introduced a new prank to the group called “The Rocky,” named for the “Italian Stallion” himself.

It involved sneaking up behind an unsuspecting victim, splashing water in his face and then immediately punching him with a boxing glove – all while the “Rocky” theme song played on a boombox.

“One time when I played the song, about eight people ducked and looked around,” Knoxville said. “It was nerve-racking.”

“The Rocky” was filmed with a camera that shoots 100 frames per second, Knoxville said. This allows the audience to see the prank – from the water splashing to the way the face reacts to the punch – in super-slow motion.

It’s just one of many new camera tricks fans will notice in the 3-D sequel.

Knoxville and Tremaine admitted they were apprehensive at first about doing the film in 3-D (”We thought it would change the process,” Tremaine said), but they eventually warmed up to it during filming and now feel they’ve made the best “Jackass” movie yet.

“You feel like you’re in the scene with us,” Knoxville said about 3-D. “It elevated the film to another level.”

Filming came with its share of problems, including injuries (Knoxville separated his shoulder when he fell off a tree dressed as Santa Claus).

And there was the occasional bickering among cast members – they don’t always laugh after getting pranked – but Knoxville said the testiness was to be expected.

“When you’re constantly giving each other hell 24 hours a day for six months, people’s nerves are going to fray,” he said.

“That’s usual. But most every time, they’re psyched because they know we got a good shot.”