Shari Theismann, With a Different Sport

The last time she modeled, says Shari Theismann, "the rules were no cellulite and no dimples or I'd sue." But that was for bathing suit photos, including the January cover of Washington Dossier magazine. Now she is promoting sportswear, specifically a line called Norwiss of Switzerland, and under long sweaters and stirrup pants there's no chance for anything to show.

Theismann, ex-wife of Redskin quarterback Joe Theismann, says that two-thirds of her wardrobe is sports clothes, the rest for black-tie occasions., Previously in sports public relations, for the moment her investment in Norwiss, originally a jeans company, is strictly her time. A financial investment will come later, she says. And the modeling? She's passing that assignment to her daughter Amy from here on.

A faithful of the Harriet Kassman shop for years, Theismann, who wears Size 2 or 4, says she has always been interested in clothes. "I've always been excited about looking well in clothes." Her father gave her credit cards as a teen-ager and said, "Go for it." Adds Theismann, "He trusted my taste and he knew I was sensible."

According to Diane Dahan, the American representative of Norwiss -- compares the Swiss company to Benetton and Esprit whose products are similar in price.

Norwiss plans to rely on Theismann's taste and understanding of the American market to guide the designing of future lines. "You'll have to come to Switzerland and give us a hand," said Dahan. Theismann seemed surprised but pleased at the prospect.

But first there will be two appearances here -- at the Home Show at the D.C. Armoryon March 1 and 2, then a health clinic at Hecht's (downtown) on April 19. For both events she will be wearing, of course, the clothing line she represents. 'Special Clothes' For Special Kids

Judi Emens has a graduate degree in special education and years of designing children's clothes to her credit. So it is no wonder that she has come up with a worthy collection of clothes for handicapped children. She has started selling them through a catalogue she calls Special Clothes.

"Parents of handicapped children always told me they wanted their children to look like all other children and have very cute clothes," said Emens. She has forfeited none of the charming look of childrenswear while making adaptations for handicaps: clothes with snap and Velcro closures, button-on waterproof bibs, and other practical accommodations suggested by parents and teachers as well as her own classroom observations in special schools.

For the moment, the clothes are sizes toddler 4 to pre-teen 14, but Emens is working on broadening the size range. The line is available by mail order only from Special Clothes, PO Box 4220, Alexandria, Va. 22303. Following the success of the first mailing last month, a new brochure is in preparation. Castelbajac's Art That Wears Well

Jean Charles de Castelbajac, who made the first quilted coats more than a dozen years ago, was stunned and disppointed to see all the quilted coats on the streets when he arrived in New York last week. He had made them originally to "merge the comfort of quilting with the movement of the body," said Castel ac, a wildlife conservationist, who had been seeking an alternative to fur. "The quilted coats I see here are structured and stiff that they restrict movement," he added. That's precisely the opposite of Castelbajac's original and consistent theme: the integration of function and elegance.

The designer was in New York for the opening at the Fashion Institute of Technology of a retrospective of his designs called, appropriately, "Innovations in Fashion." The exhibition of 100 pieces, including the first Castelbajac quilted coat from 1972, has been curated by FIT's Marty Bronson, and will be open to the public for two months.

Along with the handsome, functional designs, the show includes the creations that reflect the designer's other passion -- art. A respected collector of Neo-Expressionist

Castelbajac has showcased the work of French, Italian and German artists who have hand painted clothes. Some are one-of-a-kind pieces but others were produced in small quantities.

While in New York he talked with artist Julian Schnabel and others about working on some dress-paintings. "I'm astonished at the connection between my clothes and this country," says Castelbajac, referring not only to commercial success. He made his first coats of blankets and discovered on a visit here that the blankets he had chosen were those of the Hudson Bay Company and the American Indians. The sportswear-derived fashion, including jogging clothes that were worn by Farrah Fawcett and others in the early days of "Charlie's Angels" and others worn by Woody Allen in "Annie Hall," are included in the New York show. The flag he created for a Franco-American group in Paris was sent recently to President Reagan as a birthday gift. Hanne Merriman's Latest Pin Pals

There are just a few places you can always count on being able to spot trends -- certain shop windows, certain ads, even certain people.

One of those people is Garfinckel's president Hanne Merriman, who responds quickly to new or renewed fashion ideas as she spots them in her travels. Since her return from Europe and the Far East, Harriman has been wearing huge pins.

She spotted the pins first in England, then noticed a lot of them in Hong Kong. By the time she got to Tokyo she found the huge pins -- some Art Deco-ish, some shaped as bows or hearts -- appealing. "In one department store I couldn't resist -- I bought five. All huge," she said.

"We've been wearing a lot of necklaces and it is time for a change. With all the shirts being shown for spring, one huge pin at the neckline looks exactly right." But Will the Soup Stains Still Come Out?

"Sometimes it was hard to tell the customers from the waiters," said John Laytham, one of the new owners of the restaurants 1789, F. Scott's and The Tombs, the popular Georgetown trio taken over by Clyde's in mid-December. Laytham calls the changes in waiters' uniforms from tuxedos to weskits and long aprons "the updating of what had been a venerable institution. It also gives a crisper look." The new garb is equally popular with old-time Paris restaurants like Brasserie Lipp and New York steakhouses.

According to Laytham, it is one change in the restaurants nobody objected to. "The waiters love it. It is much easier to take care of."