Johnny Knoxville and Jackson Nicoll share ‘Bad Grandpa’ road trip memories

“We’re trying to cut off his supply of Mountain Dew,” I was warned before I walked into the room to talk to Johnny Knoxville and Jackson Nicoll. For once, Knoxville was not the primary threat I would be facing.

As we discuss in the interview, Knoxville and Nicoll worked together in last year’s “Fun-Size,” a charming kid’s comedy, and they spend pretty much the full running time of “Bad Grandpa” onscreen together. I’ve been chatting with Knoxville on and off for the last decade, both in formal interviews and just running into him around Los Angeles. By this point, I have a pretty solid understanding of the way these guys work together, and we’re not starting from scratch when we discuss whatever the latest mutation is.

That’s the way I’d describe whatever “Jackass” is. There’s no single person who defines what it is. Instead, you’ve got Knoxville, Spike Jonze, and Jeff Tremaine, all of them equal owners of it, and when they’ve done the shows or the movies in the past, there has definitely been a voice to it.

Yesterday, someone lamented in the comments section on my “Bad Grandpa” review that no one seems to remember “Candid Camera.” Not true. I certainly remember watching various incarnations of that show over the years when I was a kid, and I remember laughing at quite a bit of it. And there is certainly a continuity from what Allen Funt did to what you’ll see in theaters this weekend, with a lot of different people in the mix in between those two extremes. I don’t think “Jackass” is funny because it is innovative or because it invented the idea of shooting with hidden cameras. I think “Jackass” is funny because it feels like an experiment in random surrealism and carnage.

There is also a long tradition of giving a kid grown-up things to do and say and seeing what sort of comic gold that might yield. When Knoxville name-checked “Paper Moon” while we were talking, that was quite telling. The ’70s was a great time for movies like that, and most of them seemed to star Tatum O’Neal. They really put Nicoll through his paces in “Bad Grandpa,” and he is great at keeping a perfectly straight face no matter how crazy the situation. There is also a major moment that comes near the end of the film where Nicoll cuts loose, and the sheer irrepressible joy that he radiates during the entire sequence is impossible to fake. He looks like he’s having a blast.

But the Mountain Dew warning I got before I went in the room? Timed all wrong. By the time I got in there, the Mountain Dew was wearing off, and it looked to me like he was hitting the wall even as the interview wore on. Knoxville jumped in and did most of the heavy lifting, and I think you can see how pleased he is with the final result.

“Bad Grandpa” opens tomorrow.