Hot off back-to-back hits “Anchorman: The Legend of Ron Burgundy” and “Talladega Nights: The Ballad of Ricky Bobby” in the early 2000s, writer-director Adam McKay already had inspiration for what would become his next blockbuster.

He wanted to re-team with Will Ferrell and John C. Reilly on a project that involved collapsing bunk beds.

That became the foundation for 2008’s “Step Brothers,” McKay’s absurdist comedy that sees Ferrell and Reilly as Brennan Huff and Dale Doback, two infantilized 40-year-olds who live at home with their newly married parents, played by Mary Steenburgen and Richard Jenkins.

The over-the-top farce took longer than McKay’s other movies to gain cult status, but it has since become one of most quotable movies of the past decade. Though McKay admits that of all his films, “Step Brothers” might have had the most “absurd” premise, he still wanted to ensure the film wasn’t just filled with empty laughs.

“You want to make sure there are some real layers underneath it,” he said. “As silly as it is, we wanted to make sure it meant something.”

In honor of the 10th anniversary of “Step Brothers” McKay spoke with Variety about the scene that makes him laugh the hardest, why Ferrell and Reilly were perfect to play two ridiculous man-children, and what Brennan and Dale would look like in 2018.

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Did something specific spark the idea for “Step Brothers”? 

Ferrell and myself knew we wanted to work with John C. Reilly again off of “Talladega Nights.” We just had such a good time with him and were so impressed with him. The three of us started kicking around ideas, and I had an idea at one point that was just something about the two of them in bunk beds. Then I had the idea that, wait a minute, it’s plausible that there could be two single parents — sometimes parents still have kids that live with them at home, and they’re much older. Why couldn’t they get married and then these guys become step brothers? That was kind of it. Instantly, both of them took to it, and we started kicking around ideas from our childhood.

Did you base Dale and Brennan on anyone in particular?

It was a period in time where we were starting to see this whole thing go on in our country where there were grown adults going to Comic-Con, grown adults dressing as “Star Wars” characters, and this idea like, “What is childhood? What is adulthood?” We started talking about that feeling of, “I remember being 12 years old and the new X-Men came out.” It was just this event. We weren’t channeling specific people from our childhood, we just wanted that feeling of being 12 years old and what that meant.

What early ideas did you guys bounce around that made it in the movie?

John C. Reilly had a brother who played the drums, and he just talked about that you just can’t touch those drums because once you get the drum set right for the player, you can’t touch it. Of course when you’re a kid, all you want to do is touch drums. That feeling and that conflict is as big as a grown-up facing an indictment, the internal struggle you go through. A grown-up being pressured to turn state evidence against its fellow workers, those kinds of battles feel just as large.

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Where any other scenes inspired by things from your childhood?

I remember growing up, there was a friend of mine on the block who was a year older than me. A grown-up guy — he was maybe 23 — started yelling at us, and my friend got up in his face and was like, “I’ll knock you out.” And he backed off. We just couldn’t believe it happened, a kid made a grown-up back off. That lead to the idea of the kids beating up Will and John C. Reilly.

We also remembered, when Ferrell says he’s a great singer but he’s too shy to sing, that feeling like, “I might be the best ever at this or really, really bad.” Whatever it is, drawing or singing or baseball, you have these crazy delusions of grandeur, but at the same time you’re maybe the worst ever. There’s no middle ground at that age.

What made Will Ferrell and John C. Reilly perfect for these roles?

Both of them have a big kid-like playful side. They both have an inane sense of humor of what it means to be an adult in this world and are able to laugh at that. The root of all comedy is screwing with expectations and screwing with reality, and who does that better than kids? On another level, they are both brilliant comic actors and are incredible at improvisation. They are also shockingly grounded for as ridiculous these characters are. They play them very real. Of all the movies we’ve done, it’s probably the most absurd premise. That’s the key, playing it as real as you could. Both of them commit to just ridiculous moments that few people can.

Do you have a favorite scene?

The scene that really make me laugh, where we were like, this is the craziest stuff we’ve ever shot, for me personally is the sleepwalking scene. [Steenburgen’s character] tells [Jenkins’], “Don’t wake up a sleepwalker.” And he tells her, “Oh, that’s a myth” and wakes them up, and immediately they start punching him. That of all the scenes I’ve shot, may be one of my favorites.

Did it bother you at all when the movie opened to mixed reviews?

When you do comedies, you’re not doing them for critical reception. You’re doing them to laugh. You’re trying to do something unique, you’re trying to get a certain reaction. You don’t want to bomb, you don’t want every single review to be negative, but comedy is so subjective. You look at certain critics out there who are 70 years old, you know they’re not going to like it. Ferrell and I have pretty thick skins as far as reviews go. We really truly didn’t care about that. Also there’s a fart joke in the movie and I told Ferrell, “This guarantees it won’t get good reviews.” Actually I think [reception] was like half and half.

What line gets quoted to you most?

When the New Orleans Saints won the Super Bowl in 2010, Ferrell called me and said, “Did you read the article [online]? You should check it out.” So I did, and it describes the Saints coming in their locker room after winning the Super Bowl, and one of the players says, “It’s the f—ing Catalina Wine Mixer!” And everyone shouted back, “The f—ing Catalina Wine Mixer!” And I’m like, “That’s crazy. They just won the Super Bowl, and the first thing they said was a ‘Step Brothers’ reference.”

Where did the idea for the Catalina Wine Mixer initially come from?

Ferrell and I were talking about the most boring, dry, grown-up event that, for some reason, people think is a huge deal. Ferrell just said the phrase, Catalina Wine Mixer. I’m not from L.A., so I didn’t know anything about Catalina. I just thought it sounded funny, and I thought idea of a wine mixer was the perfect thing to make a big deal of. We went out to scout Catalina Island, and it’s very beautiful out there, but it’s not much of a town. I came back very baffled and I was like, “Ferrell, Catalina Island is pretty, but there’s not much out there.” He’s like, “I know, that’s why I said it.” He was laughing because we took a whole crew out there to scout it. Catalina Wine Mixer just sounded absolutely ludicrous, and we loved the joke that the guys from a helicopter leasing company just treat it like it’s freaking the end of the world — the level of how jacked up they are about it. That phrase just repeated over and over just made us laugh harder and harder.

The film name-checks a lot of people, like John Stamos, Fergie, Oprah, and Barbara Walters. Have any of them ever said anything about it to you?

Who was it that told me they saw John Stamos… what was the line again?

It’s “If you were a chick, who’s the one guy you’d sleep with?

They both say “John Stamos” at the same time. So I guess Ferrell saw Stamos, and he was like, “Hey man, thanks for that!” The other great one is Ferrell was at an airport or something and Randy Jackson is there and he comes up to him and he’s like, “Hey man, thank you for that, but why me? Why’d I have to autograph the samurai sword?” [Laughs] Ferrell was just like, “Why not? You’re a famous guy!” I guess the only guys who wouldn’t like being name checked are the guys with Derek [Adam Scott] on the fishing trip. Mark Cuban, Bobby Flay, Jeff Probst, and Chris Daughtry from “American Idol.” But the truth is even with those guys, it was just supposed to be the alpha-male types. I’m sure they are all super nice guys. That joke was just square jaw guys on a fishing trip.

Everyone always wants to know if you’d do a sequel to “Step Brothers.” Have you given it any more thought? Why did you feel “Anchorman” lended itself to another movie as opposed to your other films?

In the case of “Anchorman,” those characters can age, and the news business has changed and become so many different things, it naturally lent itself to a sequel. We certainly felt like we had a couple other things to say, especially with the creation of trash news. We loved the idea of Ron Burgundy being responsible for that. With “Step Brothers,” it’s tricky. We have a couple ideas that we liked through the years. The world is so topsy turvy right now that it would really be some idea where you jump out of your chair to do this. I don’t know, I have definitely learned to never say never. There was a point where I said I would never do any sequel, then it became like, “Can we pull it off? Can you do a second chapter?” A lot of what works with comedies is the surprise of the fresh new world that you’re seeing.

Given the state of the world today, do you think “Step Brothers” would look different if it was made in 2018?

Oh god, yes. The dilemma at the center of the movie is, “Why do I want to grow up when adults look this way?” [Laughs] They look a lot worse right now. It wasn’t great back then either, but the world that Dale and Brennan would be stepping into would be more tumultuous and frightening. You’d have the same structure, but it would be hard not to mention Trump. All the stuff that’s going on would have to be an element in it. The second act you’d have Dale and Brennan as big Trump supporters and go hard core right wing. It’s funny to talk about movies in different times. It’s almost impossible to do because that movie is such a product of when it was made. I can’t imagine we wouldn’t have jokes about the insanity that’s going on right now with the political system. That would have to pop up in at least one of them. Dale or Brennan being a die hard “Make America Great Again” guy would be too hard to resist.

So instead of a sequel, maybe just reboot the movie in the Trump era?

That’s actually not a bad idea. It’s a clever way to do a sequel. Just do a remake, but let the times wash over it. Can you do a comedy about this time? At one point, I’ve got to try. Is there a way to laugh at this? We will see. The whole comedy world is reorienting itself right now, trying to figure out how to deal with this insanity that we’re living in.

A Trump-centric project might be more of something you have to look back at and laugh.

In other words, you have to have gotten through it to look back and laugh. That would be my preference. That all of this ends and later we can laugh about it.