By the mid-’70s, Cheech Marin and Tommy Chong — a.k.a. Cheech & Chong — were among the most successful comedians in America, thanks to the success of albums like 1971’s Cheech and Chong, 1972’s Big Bambu, and 1973’s Grammy-winning Los Cochinos. Like many comedy acts before them, the pair began to contemplate making a movie, although, according to Chong, the main impetus behind their move to the big screen was his reluctance to return to the Antipodes.

“We got tired — or at least I got tired — of touring Australia,” he recalls to EW with a laugh. “Every time we’d go to Australia, we’d miss summer here, and we would have winter in Australia, and then we would come back in time for winter here. It went on for three years. So the fourth year I said, ‘I don’t want to go to Australia, I’d rather do a movie!’ Because we stopped going on the road, we ended up with Up in Smoke instead.”

Australia’s loss would be the stoner comedy genre’s gain. Cheech & Chong’s debut film, which marks its 40th anniversary on Sept. 15, cost less than $1 million to make but scored $44 million at the box office. Fans lined up to witness the picaresque adventures of Chong’s weed-blasted character, Anthony “Man” Stoner, and Marin’s equally marijuana-friendly low-rider, Pedro De Pacas.

“The plot of Up in Smoke — and there is one! — is that two guys meet, they want to form a band, but first they need to find a joint,” says Marin. “And therein lies your plot!”

Up in Smoke cemented Cheech & Chong’s reputation as counterculture icons, and four decades on, it remains a beloved comedy. It could even be argued that the sympathetic depiction of the two lead characters helped pave the way for the decriminalization of marijuana use in California and elsewhere.

“Well, one can only hope!” Marin says. “I don’t want to claim any responsibility that’s not there. But it didn’t hurt the attitude, you know, because here were these two street characters, they were amiable, and there wasn’t anything nefarious about them.”

Up in Smoke was directed by the pair’s record producer, Lou Adler, and was originally planned as a showcase for their best-known sketches.

“Lou wanted the movie to be Cheech & Chong’s greatest hits,” says Chong, who co-wrote the script with Marin. “But both Cheech and I decided that the low-rider character and the stoner would be the main characters. We just took it from there, and we kind of wrote as we went. You would go to the script when you had nothing else to do, you know. Then you’d look at the script. But for the most part, it was a good improvisational movie.”

“We had bits that we wanted to do, but we kept making them up as we were going along,” Marin recalls. “Luckily, we had hired actors that were improvisational actors and a crew that could adapt to quick changes. ‘Okay, after lunch we’re shooting this other scene, it’s not in the script.’ Everyone didn’t get freaked out. Everybody was on the same page creatively.”

The film’s cast also included Stacy Keach, who played the narcotics cop, Sergeant Stedenko.

“The character that he played was a real cop that used to try to bust Cheech and I,” says Chong. “His name was Abe Snidanko. And so, when it came to naming the character, I pulled Abe’s name out of the memory bank and we made Abe famous. He never did really forgive us.”

“Stacey Keach was amazing,” Marin says. “He brought this discipline to the production that we had not had, because we didn’t have any experience as film actors. He got his little crew of cops together, and he would rehearse them all the time and come up with their characters. We told him, ‘Here’s the information you have to get across, and this is the setting in which you’re doing it. Okay, go!’ He had actors that kept practicing until they got their characters right, and then once they got their characters, anything they did was in character.”

In the film, Man and Pedro are either high or looking to get that way. But Marin is keen to point out that he and Chong were always straight when in front of the cameras.

“You have to have concentration and energy over a long period of time, every day,” he says. “If you’re getting high every day, that’s not going to happen.”

Chong recalls that one of the many people to note and appreciate the ultimate success of Up in Smoke was Warren Beatty.

“Cheech and I were on the Paramount lot,” he says. “We’re walking, we were trying to get another deal going, and Warren Beatty pulled up in his car. And he said, ‘You guys have no idea what you’ve done.’ What he was meaning was, we had a number-one movie — and Warren Beatty, he had the same thing with Bonnie and Clyde. So he knew the odds of coming out of the gate and then winning the jackpot the first time around. That’s my favorite memory. That was the only time Warren Beatty ever really talked to us, because he’s very, very quiet. But he had to stop and give us his congratulations. That’s when Cheech and I looked at each other and said, ‘Wow, we really did [it], didn’t we?’”

Cheech & Chong would continue their onscreen partnership in a string of films, including 1980’s Cheech and Chong’s Next Movie and 1984’s Cheech & Chong’s The Corsican Brothers, and they continue to perform live to this day. Meanwhile, the Grammy Museum in Los Angeles is currently commemorating the 40th anniversary of Up in Smoke with the exhibition Cheech & Chong: Still Rollin’ — Celebrating 40 Years of Up in Smoke.

“Oh, it’s wonderful,” says Marin. “The Grammy Museum came to us, and they wanted to celebrate the 40th anniversary of this thing, and kind of all things Cheech & Chong. So they built this display that has various aspects of our career, and aspects of Up in Smoke, and all those things it took us to get there. It’s very interesting.”

“It’s a big celebration of the recognition of pot,” says Chong. “It’s like we gave a Grammy to marijuana!”

Image zoom Alison Buck/WireImage