Remember "Ninja III -- The Domination"? That movie where the guy crushes a golf ball with his bare hand, slices, dices and makes julienne fries out of a bunch of cops before he disappears in a cloud of smoke? All in the first 10 minutes?

If not -- even if you don't know what a ninja is -- don't worry. The point is, name it "ninja" and it will sell.

In fact, ninjas are Japanese warriors trained in ninjitsu, a 2,000-year-old martial art that, unlike judo and karate, permits the use of such devices as blowguns and hook knives. But consumers don't seem troubled; they just lay down their dollars.

"Ninjas are more into clothing . . . In Bruce Lee or Chuck Norris movies, they're just squaring off without any fancy regalia or specific weapons," says Mike Broidy, senior publicist for Cannon Productions, which released its fourth ninja movie, "American Ninja," this weekend.

Parfums de Coeur calls a new fragrance Ninja because it's "short, pronounceable and oriental," says the company's president, Mark Laracy. He's sure no one will associate the scent with Japanese assassins. "Most Americans don't really know what the word means." But that doesn't mean they won't go to ninja films or buy ninja mechandise.

The marketplace even has a spot for a "throwing star," a sharp-edged pocket weapon tossed like a Frisbee. What could be more American?

The American fad has already sparked a response. Maryland Del. Nancy Murphy cosponsored a bill, which was enacted July 1, naming the star a deadly weapon. Murphy says the bill is intended to discourage kids infected by the "kung fu epidemic" from bringing stars to school. "In about 15 minutes you could become proficient enough to hurt someone," she says.

But those selling the ninja image are not complaining.

Cannon Productions' low-budget "Ninja III -- The Domination," released last September, grossed $7.6 million. "Revenge of the Ninja," screened in September 1983, grossed $13.2 million. Not exactly box-office smashes, but, as one film distributor puts it, "success is relative. How much you make on a film depends on how much you spent producing it." He calls the ninja films "very successful."

Kawasaki Motors Corp. introduced the Ninja 900 ($4,500) last year and the Ninja 600 ($3,400) this year; the red-and-black sport motorcycles are selling better than any of the company's other bikes. "It's appealing to the eye and it has high performance, and that combination is like a one-two punch," says Mel Moore, public relations manager for the company.

Buyers have snapped up about $20 million of Ninja perfume (and talc, body spray and lotion) since it went on the market four years ago, according to Laracy. The perfume is an inexpensive ($7.50 an ounce) imitation of the spicy Opium and Cinnabar scents, which sell for three or four times as much.

Then there are the sweat shirts, uniforms, posters and books.

Some object to the way the ninja fad is sold. Steven Hayes of Ohio, who has studied ninjitsu for 10 years and has written eight "how-to" ninja books (a ninja novel is due this month), says he refused to advise Cannon executives on their movies. "It would have been like calling the archbishop to help with an episode of 'The Flying Nun,' " he says.

Eric Van Lustbader says his 1980 novel "The Ninja," which was on The New York Times best-seller list for 22 weeks, sparked the public interest that led to what he calls "exploitation" films.

"When these disciplines are transported to western societies, the whole notion of mental discipline gets lost," says Van Lustbader. "Being self-disciplined is not very appealing to the American public. They want to put their fists through a brick or punch somebody out, but they don't want to encumber themselves with the philosophical aspects of the martial arts."

The discipline calls for understanding "intrinsic energy concepts" like ki, a force in living things. First step to harnessing the power of ki: "Relearn how to breathe again like a child."

Having "mental discipline" helps ninjas hold their breath, "fade into the night" and "live with the animals" (not necessarily in that order), according to Lustbader.

Those who feel the art has lost something in the translation to movies like "Shogun's Ninja" (Media Home Entertainment) and the NBC-TV series "The Master," which aired 13 episodes in 1984, should rest assured that ninja fans are not without doubts.

Dylan Scott, 12, of Rhode Island, who first got interested in ninjas by playing a video game called "Ninja Gun," has seen all the movies but is just a bit skeptical. "In 'Ninja III,' the ninja drilled himself through the ground, you know? I'm not really sure they can do that."