America's favorite granny

When youngsters spot Loretta Tupper on the street, they usually shout ''There goes the Fruit of the Loom lady!'' Their parents are just as likely to respond with a rollicking ''Whoop-dee-doo for my Subaru!''

Whether she's cooing over flea collars or dashing pies in another actress's face with a warning ''Keep your paws off my Parker,'' Mrs. Tupper is fast becoming the favorite granny of some of television's most entertaining commercials. She pushes detergents and rental cars, American mufflers and English muffins with an enthusiasm that's the envy of Madison Avenue.

''I love every minute of it,'' she crows. ''At an age when most people are going crazy trying to find something to do, I'm going crazy trying to catch a cab to the next audition. I'm 76, and I'm having a ball.''

In a medium where the hard sell often has to be made in fewer than 30 seconds , Mrs. Tupper's chirpy voice and putty-like expressions are among her most marketable talents. Dressed in a New York Yankees uniform with a bat slung threateningly over her shoulder, she could take on George Steinbrenner single-handedly. But put her in a blue flowered silk dress fastened at the neck with an antique cameo pin, and she looks like she should be saying grace at a Norman Rockwell Thanksgiving dinner.

Her cheeks are rouged to a chiffon pink for the day's auditions, and her cloud-blue eyes do a lively boogie as she talks about her TV image and her favorite kinds of commercials. ''I'm no cutie-pie,'' she says. ''I only do funny or feisty parts. None of that sweet grandmother stuff for me.''

One-Take Tupper, as she's affectionately been dubbed by the directors she works with, brings to her rising new career in TV commercials the background of a long-time veteran of classical music, vaudeville, and radio. An acclaimed piano prodigy at age three, she had been offered scholarships to a number of music schools by the time she was six. At 14, she put together her own performing troupe - consisting of violinist, singer, ballet dancer, and guitarist - and took to the roads up and down the East Coast and into Nova Scotia and Canada on the then-popular Chautauqua concert circuit.

On one memorable tour in West Virginia, she arrived at a local hall one evening to find a piano with only 25 keys instead of the usual 88. ''Now you just try to play Beethoven or Liszt with only 25 keys!'' she hoots. ''I checked with my musicians and asked them if they happened to know any tunes like 'Turkey in the Straw' and 'Arkansas Traveler.' They said if I could start them, they could follow along. And that's what we did - ad-libbed a real live hoedown all night long, and the audience loved it.''

That kind of ingenuity and resourcefulness saw Mrs. Tupper through several years as staff pianist for a number of stations in the early days of radio. At Cleveland's WHK and later at Buffalo's WBEN, she often opened the broadcast day at 6 a.m. with a rousing rendition of the Star Spangled Banner, played through her repertoire during the day, and signed the station off the air at midnight with the national anthem, tapped out at a tempo that matched the hour.

She and her guitarist-comedian brother teamed up as the popular vaudeville duo ''Jack and Loretta Clemens,'' and went on to perform on many of the first radio shows broadcast live from New York City, including the Gibson Family and the Phillip Morris Show.

After marrying violinist Frederick Tupper, she took time off from show biz in the early 1930s to raise a family. It wasn't until 1969, when she was playing piano at New York's Ballet Arts studio, where her daughter was studying dance, that Mrs. Tupper was rediscovered. The photographer-father of two of her voice students, a long-time fan from her vaudeville days, took a batch of publicity shots and sent them to a number of agents in the city. Within weeks Mrs. Tupper had landed her first television commercial, advertising Parker Pens.

Since then, her days have been a non-stop round of auditions and voice-overs. In 1977 she won a Clio award, advertising's Oscar, for her first Fruit of the Loom commercial, and that same year she played a small part in her first film, Woody Allen's ''Annie Hall.'' Several movies have followed, and this December she can be seen in a cameo role in ''The King of Comedy'' with Robert DeNiro and Jerry Lewis.

Although Mrs. Tupper dreams of someday appearing in a film with her favorite actress, Katherine Hepburn, she insists that the most intelligent actress she's worked with so far was the dog who shared the billing in a recent Sargeant's flea collar commercial. ''The old man and I fluffed our lines every time during filming,'' she recalls, ''but that dog was just as calm as could be. She intimidated us like crazy.''

As much as she enjoys working with animals, Mrs. Tupper says she's turned down all requests from directors who've wanted to use some of her own five cats in commercials. ''They're wonderful, normal pets,'' she explains, ''and they'd just get nervous with all those hot lights and wires. Besides, they wouldn't know they were getting any checks for their work.''

When she's not dashing through airports, yelling ''Go, O.J., Go!'' or snuggling up to Rosie the chimpanzee in an ad for butane lighters, Mrs. Tupper spends much of her free time with her grandson, Tommy. But she doesn't think of herself as a traditional grandmother.

''I used to love to bake, but I'm the world's worst knitter and sewer,'' she says. ''What I probably miss most about working so much is getting my hands in the soil and planting things. Every once in a while, I just have to get out in the country and run around barefoot.''