Cheech and Chong don't look like bums anymore. In fact, Cheech Martin and Tommy Chong have escaped the barrio forever and are flying high on two magical drugs: popularity and commercial success. As a stand-up comedy team, they had thousands of followers for their routines about ghetto life and the constant lust for all types of marijuana. In laconic style, the two based their humor on strange, burned-out characters whose off-the- wall repartee generated easy laughs. These characters often spoke in grunts, and halfsentences, peppering their dialogue with "yeah, man's" and "yeah, so you know's." Their most famous routines include a dreamy song called 'Basketball Jones"; and a sequence whose ear-shattering punch line is delivered by a nun to her high school class: "SHUT UP!!!"

Two years ago, the pair embarked on a film project: Up in Smoke, a picaresque comedy of two low riders in search of the biggest marijuana joint in the world. Surprisingly, it grossed $104 million world-wide; not surprisingly, Universal eagerly produced their next film, Cheech and Chong's Next Movie, which opens today (see review). In Boston to publicize the new film, the duo submitted to an early morning press conference.

They arrived dressed in the casual splendor they can now afford: Cheech in a T-shirt, bright green pants and flip-flops; Chong all in white, with high-top wrestling sneakers, a green translucent belt and tinted glasses. "Hey," says Cheech, gesturing at his clothes, the microphones, and the cameras and smiling knowingly, "We're not as dumb as we look."

They certainly do not look like the characters they play in their latest film, spaced out low riders in search of women, drugs and a good time. But their tan, Hollywood looks cannot hide their passion for pot and they, as cultural heroes for millions of fryheads, are quick to offer counsel on the subject of marijuana.

"We don't think it should be legalized," says the bearded Chong, who directed Next Movie. "It would put too many dealers out of work. Plus, the government has this deal where they seize the smugglers' boats and sell them back to the dealers--it's a small industry that might hurt the economy if it failed."

"In Canada," adds Cheech, "the police use our films as training: how burned out you can get. When it comes to making films about drugs, if it wasn't us, it'd be somebody else. I believe there's good and bad dope," he continues, "If I believed dope was bad for you, well, you know..." and his voice trails off in a degenerate sigh.

Their secret, they divulge in sober tones, is that they do what they do to the best of their ability. "It's like punk rock music," Cheech pipes in. "The best musicians in the world can't play that crap. The best art in the world comes from the soul."

Not that they consider what they do art. To them their work is more of a game, a vacation from their lives and their wives. Tommy Chong is the instigator--"He was always the guy who'd hang around the class clown and say, 'Hey, why don't you do this"'--but more often they work in tandem.

They try to work at a regular pace. "We'll come into the office late and then we'll go to lunch," laughs Cheech. "We write like writers," says Chong. "We start writing eight hours before our deadline and then tell our editor that it could've been better if we'd had more time."

The resulting script for Cheech and Chong's Next Movie was not a script at all. They simply gave Universal a list of the sets they wanted built, then cast the type of actors and comedians they thought could improvise well in front of the camera. Then they set to work, with only a vague notion of plot or dialogue.

As they rewrote the shooting "script" everyday, the production went through three script girls. "The first one was an alcoholic," says Chong seriously. "She couldn't drink and write at the same time. I forget what happened to the second one."

Chong learned how to direct as he went along. "In a comedy," he realized, "you need pace instead of plot. It's so hard to get all the elements working. I have tremendous respect for any filmmaker. To finish it, then to have it shown, then to have it accepted--WOW!"

Directing also gave Chong new perspectives on producing and acting. "It's really hard to spend money in a Cheech and Chong film. We spent a lot on the space ship (a prop in the film) but it hit the floor. We spend half the film just talking in the living room.

"I also realized that the director sees things totally differently from the actor. He's gotta keep the whole thing in his head. As the director, I'd think I might want a car crash or some other silly stuff but then I'd look at myself as the actor and say, 'Hey, I'm not gonna do that shit!'

"Doing a comedy is a lot like the clown at a party. If he has restraint, he walks away and you say, 'Who was that guy?' But if he does one lampshade joke too many, you go, 'Who was that asshole?'"

Both Cheech and Chong agree that much of their humor comes from watching other people in funny situations. "We're a good audience, shopping cart people can make us laugh for days." Putting together material is a lot like forming a band, says Cheech. "It's really a joy when you can find a good bass player."

They say they appreciate nearly anyone who has the guts to stand up and tell jokes. But they can't stand canned humor. "You know, you're watching a movie and you can tell: 500 feet to the joke, 250 feet to the joke, 100 feet to the joke, The Joke, You just passed the joke..."

They snap at stupid questions: "What's our message?" responds Cheech to one serious newsman. "The message is that there is no message. That generation has grown up. There's even less no message for them."

"Our audience? I think we cut across the counter-culture. We're over the counter."

"What doesn't the public know about us? Our background in art. Most people don't realize we are recognized experts in French Impressionism."

Someone points out that both Cheech and Chong like to sing and play a lot of music. "Are we a rock group?" Cheech chortles behind his huge mustache. "No, I like to think of us as spokesmen for an entire generation."

"How do we handle groupies?" Tommy Chong grins. "Like this--" He wraps his arms around an imaginary woman and squeezes while Cheech leans back in his chair and laughs.