Andrew Emery had a feeling he was on to something when he dreamed up the concept for his topless doughnut shop.

"It just struck me that it would be something a little novel," says the 72-year-old Emery, who dabbled in real estate and a flower business before starting his new venture last November. "Sometimes I wake up in the middle of the night with crazy ideas like this."

R Donuts -- "R"-rated for risque', because this otherwise ordinary doughnut shop features waitresses in the almost-altogether -- has been thriving ever since.

Open from 6 in the morning till 8 at night, seven days a week, it sits on South Federal Highway, a promenade known for its "adult theme" motels, in what was once a Burger King. "NO CAMERAS PLEASE," a sign at the cash register admonishes customers, who must be 18 or older. Also "PROPER ATTIRE REQUIRED," whatever that may mean.

The faded orange interior is clean and well lighted, and might even be called sedate -- were it not for a squad of cheerful servers clad only in running shorts or bikini bottoms, many of these stuffed with U.S. currency. With cups full of steaming coffee and plates full of doughnuts and muffins, they dash among the tables and up and down behind the counter -- for, on this particular spring day, the place is packed.

The clientele is oddly subdued. It consists mainly of men. They glance furtively this way and that, somehow managing to keep heads and necks in perfect alignment. Only the eyeballs swivel.

Aside from this contingent -- who appear to have stopped in on their way to work -- there are also a gaggle of college kids and more than a few out-of-towners.

"If you've seen one, you've seen them all," says one of the latter, Eugene Cohn, not making it clear precisely what he's referring to.

"Oh, stop being such a motor mouth," scolds Cohn's wife, who declines to give her name. It seems the Cohns just happened by with their daughter, a student at a nearby community college, and another couple from Fond du Lac, a town of 35,000 in Wisconsin.

"You're the motor mouth, Mother!" Cohn replies with a cackle.

Occupying the seats next to him at the counter are Alan Sheen, 26, and a buddy named Mike. They say they work side by side in a beer bottle factory in Hamilton, Ontario, and struck out from the Great White North for Fort Lauderdale after seeing an item about R Donuts in the Hamilton Spectator.

"It's great, it's beautiful," says Sheen, eyeballs at full swivel. "The guys back home -- they won't believe it."

The waitresses range in age from 18 to 38. They range in size -- according to their own calibrations -- from "bodacious ta-ta hooters" to "sunny side up."

"This is a lot different than striptease," says Charlotte Hynes, 25, the first waitress Emery ever hired. "I don't have to dance. I don't have to sell a $50 bottle of champagne."

"We don't skimp on anything," the proprietor says, surveying his establishment with evident satisfaction. "Our donuts are extra-large, not the small donuts. The orange juice is freshly squeezed."

It's just about noon and, for waitress Liz Snyder, time to knock off work. "Andy," says the 21-year-old former "TV repair person" from Elkhart, Ind., to the boss, "I'll just go ahead and put my shirt on." But she pauses for a moment to chat, resting her elbows on the counter top.

"The only time I ever felt self-conscious was when my mother came in," Snyder says. "I thought she was gonna kill me, but she just laughed and laughed. The customers are great -- except for the college kids. They just don't know how to act in front of a girl without a shirt."

"At first I didn't like it," says Snyder's husband Hugh, 24, who works as the maintenance man at R Donuts. "But the people who come in here are basically real groovy."

Not everyone would agree, of course. The authorities, while not empowered to shut the place down, wouldn't exactly be grief-stricken if it died a natural death -- although they might be saddened to know that Emery has a 20-year lease. (Neither the mayor nor the chief of police was returning phone calls on the subject.) Early on, the establishment sustained a brick hurled through a window. And on opening day, some area residents set up a picket line to protest its presence.

"We just feel we already have our share of these kinds of things in the neighborhood," says Ron West, president of the Harbordale Portside Civic Association, which staged the protest but disavows the brick. "We're not wild-eyed, right-wing brown shirts over here."

As for the no-shirts, they have been attracting as many as 1,000 customers a day, Emery says. It's a lot more exciting than the photo album company he owned in Morristown, N.J., before he retired more than a decade ago.

"I'm one of these workaholics," he says. "I don't believe in retiring."

If he looks fatherly -- a wiry, gray-haired fellow with a kindly smile -- it's probably because he's the father of two daughters and a son. "He usually gets an idea, and sooner or later he follows it through," says the son, Gary Emery, 42. "He's got a very young mind, which is part of staying alive."

Andrew Emery, for his part, has his hands full giving interviews, minding the store and going through a sheaf of applications from would-be waitresses -- as many as 30, he says, for every hire.

As for qualifications, they certainly have nothing to do with mathematical ability. Emery says that for simplicity's sake, everything is priced in multiples of a dollar -- $1 for a doughnut, $5 for a sandwich.

"That way," he says, "the girls don't have to worry about 5 cents here or there."

Neither, it would seem, does Emery, who has been selling R Donuts coffee mugs and T-shirts in similar multiples -- and, as if one R Donuts shop were not enough, hopes to license the name at the rather bodacious multiple of $35,000 a pop.