Justin Long was the king of pranks on the “Live Free or Die Hard” set.

The actor, 40, stopped by PeopleTV’s “Couch Surfing” and recalled the time he pulled off an epic practical joke on co-star Bruce Willis during the filming of the 2007 sequel, the fourth film in the “Die Hard” franchise.

According to Long, before shooting a stunt in an automobile, Willis warned him, “You’re going to want to have some Dramamine because it’s going to be a bumpy ride.”

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He explained that usually filmmakers can fake how fast a car is going for a scene, but for this particular stunt, the car would be swung around particularly fast. Long, however, used this knowledge to his advantage, shovelling oatmeal into his mouth just before the cameras began to roll.

“We finished the take and the camera guys kept rolling because they knew I was going to do a bit,” explained Long. “And Bruce goes ‘How you feeling kid, huh? I told you — you should’ve taken that…'”

Before Willis could finish his sentence, Long spewed the oatmeal all over the action star’s shirt, making it appear as if Long had a bad case of motion sickness.

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“I’ve never seen John McClane panic because he doesn’t panic in the [‘Die Hard’] movies, but he f**ing panicked,” Long revealed. “He was really freaking out.”

Long also touched on Steve Job’s creative input on the famous “Get A Mac” commercials.

“One, in particular, I remember, Zach Galifianakis played, like, a drunken Santa Claus,” Long recalls. “And [Apple] said, basically, that Steve Jobs preferred when they weren’t super funny… because he thought it would detract from the point of the commercial. He thought if people were too focused on the humour in it, they would lose sight of the product.”