LOS ANGELES - David Zucker opens a manila envelope and pulls out a sheaf of glossies documenting his long, strange association with one Robert Weiss.

“I’ve brought some evidence of the movies we’ve made together,” Zucker says. He seems a little nervous, a little squirrelly. Weiss sits next to him on the settee, a bear of a man, noshing a bagel and shmear, warily. “I don’t have pictures of our relationship,” Zucker explains.

“The police,” says Weiss, chewing slowly, “have those.”

And they’re off. Zucker and Weiss have been making films for three decades. Their collaboration has resulted in the iconic touchstones of late-20th-century cinematic parody, such as “Airplane!,” widely acknowledged as the progenitor of the feature-length spoof since its 1980 premiere. The form has since been endlessly imitated and retooled, and consistently profitable. Their original classic was followed by the “Naked Gun” series and the current “Scary Movie” franchise, with the nationwide release of “SM4” on Friday.

If you are unfamiliar with the genre, you need to know this: In “Scary Movie 4,” escaped monkeys drive forklifts.

A Michael Jackson look-alike comes to save the little children from a war of the worlds. The real Dr. Phil amputates his own foot. Charlie Sheen dies of lethal erection. Cloris Leachman? You don’t even want to know.

“Scary Movie” mocks horror films and pop culture. The Zucker-Weiss product is spoof, it is slapstick, it is stupid. And it has made Leslie Nielsen rich and famous beyond his wildest dreams.

Zucker places his photographs on the glass table. Here is a picture of him and Weiss, along with their other longtime collaborators Jim Abrahams and David’s brother Jerry Zucker, all sitting down, poring over a script, while behind them three naked women are writhing seductively, bound in chains.

“I believe this is a script conference,” Zucker says, from the set of their first film, “The Kentucky Fried Movie,” released in 1977.

“We can show our kids someday,” Weiss says. “Here’s Daddy hard at work.”

They can do this all day long.

When Weiss, who has fallen into the role of producer, and ZAZ, as the writing-directing team of Zucker-Abrahams-Zucker came to be known, tried to pitch “Airplane!,” the studios were reluctant.

“Nobody would do it. No way. Impossible,” Weiss says. “Thrown out of everywhere. There’s the unwritten rule: They will only let you do what you have done.”

Because there have been so many imitations, we forget that “Airplane!” was once unique.

“It was the first full-length film parody,” says Zucker. “It was comedy without comedians - that was what was different about it.”

Before, there was sketch comedy. There was Mel Brooks and “Blazing Saddles,” a spoof of westerns, but it starred comedians.

“Airplane!” was a spoof of the disaster movies popular in the 1970s, especially the “Airport” films based on Arthur Hailey’s best-selling potboiler, but it had straight actors like Lloyd Bridges and Peter Graves.

The “Naked Gun” series parodied cop shows, with washed-up B-movie cop actors. The “Scary Movie” franchise does horror flicks like “Saw,” “The Ring” and “The Grudge.”

Where did this idea of the spoof come from?

“We’d watch the old, late-night movies, and we’d talk back to the screen,” Zucker says. “The breakthrough we had was saying, OK, we’re going to re-create those old movies. But have actors speak lines we would have dubbed.”

Weiss: “Also one thing we all shared in our background growing up was Mad magazine. The feature called ’Scenes We’d Like to See.’ Six panels. First five were straight setup, a western, a gangster movie, and in the last panel there was what we call the switch and spin. Where they’d reverse your expectations, do something wildly different. This had always made us laugh growing up. And was the philosophical underpinning of this kind of humor.”

Zucker: “Which we continue to this day. In ’Scary Movie 4,’ the first thing you see in each scene is us putting the audience in that world. We start out very seriously. There’s Tom Cruise’s house in ’War of the Worlds.’ Or there’s Sarah Michelle Gellar’s house in ’The Grudge.’ Or the bathroom from ’Saw.’ Always starts as a serious setup.”

Then the joke. They hope.

“These things work because our audience has watched literally thousands of hours of television and film,” Weiss says. “And so what we want to do is stimulate the archetypes and images they already have in their brain, and then the audience starts to work for us. When these jokes work best is when the audience is most surprised where we take them.”

Zucker: “If you have people winking and not playing it earnest and it doesn’t feel like a real movie, then you have layers between you and the jokes we want to make. You’re sitting there expecting what is the next funny thing. Chevy Chase comes on-screen and you’re waiting for him to do some shtick. We don’t do that. When Leslie comes on, everything he says is a surprise because he says it with the utmost sincerity. We hire these guys because they’re straight actors.”

They got leading men like Bridges (as a glue-sniffing air traffic controller) and Graves, who plays a gravel-voiced pilot and invites young Joey up to the cockpit and delivers that immortal line: “Do you like gladiator movies?”

Their casting director said: Leslie Nielsen? Are you crazy? “Leslie is the guy you go to the night before,” Weiss says. “When you’re desperate. He was the most obscure character actor.”

“But we knew him, from these half-assed B-movie swamp odysseys,” says Weiss.

“Nobody knew there was this guy inside him,” Zucker says. “He’s smart. He knows not to crush the scene. The advice I give is let the lines do the work. Don’t put any spin on it.”

“There are two kinds of actors you want,” Weiss says. “The smart ones who know not to help. And the ones who don’t know what’s going on, and they’re OK too.”

The Zucker-Weiss formula also includes the liberal use of look-alikes. The duo explain that often they don’t want the real person. “Why have Michael Jackson making fun of himself, because it is not as funny,” says Zucker.

Ditto for Oprah. Mike Tyson. Tom Cruise. President Bush.

Or O.J. Simpson, who appeared in their “Naked Gun” movies as the dim bulb Detective Nordberg (before the deaths of Nicole Brown Simpson and Ronald Goldman).

A return cameo for the Juice?

Ummm. No. “How do we have O.J. back making fun of himself?” Zucker says. “See? It doesn’t work.”

The spoof genre is generally “critic-proof” fare. “Scary Movie 3” garnered $110 million in domestic box office sales. In all, their spoofs have grossed $446 million domestically.

At the end of the interview, we head toward the valet parking line. Zucker pauses. “Can you spin all this in the most favorable light?”

“We’re not evil mercenaries,” Weiss says.

“Make us seem erudite,” Zucker suggests.

“Not complete illiterates,” Weiss says.

“You know what reporters always like?” Zucker asks Weiss. “They like a little something,” a way to end their articles, what’s called a kicker. “Here’s a little something.”

He offers a crisp $20 bill.

When we play along, reach out, Zucker says, “You don’t have any change, do you?”