The Macy's boys' department in Stamford, Conn., is almost as quiet as a playground after recess. Unfortunately for the after-schoolers who straggle in, the very last Simpsons T-shirt went home days ago. ''They sold right out,'' the wide-eyed sales assistant says.
Across the mall in the young men's shop at J.C. Penney, it's the same story. ''As soon as they came in, they went out,'' says a weary sales person as she surveys empty racks where Simpsons T-shirts, boxers, and baseball hats made brief appearances.
The Simpsons has raced up the Nielsens since its premiere in December. And it looks as if Simpsons products are going to be just as popular. T-shirts and baseball hats are only the beginning. Also in the works: everything from talking Bart dolls to air fresheners labeled ''Smellerific'' (a favorite Simpsons term). With approval from Fox Broadcasting, which controls Simpsons merchandising, about 70 licensees including heavyweights Mattel and Nintendo are expected to market more than 200 products.
''The thing we are really anxious to do is to not have it get out of hand, like Batman or Ninja Turtles,'' says Matt Groening, the show's creator. ''The show comes first. But we do understand there are people who want merchandise and we'll try to help them.''
Bart, the brattiest of the Simpsons bunch, has emerged as the new darling of merchandising. His crown-like cranium graces all manner of merchandise men's boxer shorts and bumper stickers are two examples and, to borrow a Bartism, the rate of sales is ''radical, dude.''''Mark McDevitt, an assistant buyer at J.C. Penney's Dallas headquarters, says, ''We are selling roughly 40 to 50 percent of our (Simpsons) inventory every single week. When you say that for 1,000 stores on average, those are incredible numbers.''
''Not since The Flintstones has an animated project been able to touch a little something in everyone like this,'' says John Bower, vice president of marketing sales for Shirt Shed, one of two Simpsons T-shirt manufacturers and distributors.
More fun for Simpsons fans: kites, buttons, coffee cups, three kinds of bubble gum, bed sheets, sleeping bags, and large posters of Bart bellowing, ''Stay outta my room, man!'' Simpsons Halloween costumes, talking toothbrushes, and watches also are planned.
Gregory Fischbach, chairman of Acclaim Entertainment, a Nintendo software marketer and distributor, is planning three Simpsons video games for 1991. ''The Simpsons characters have real staying power and won't pass through the culture and go away,'' he says.
But there are those who sound notes of caution. Gary M. Jacobson, a financial analyst at Kidder Peabody in New York, says: ''With any fashion fad, you've got to react quickly, and I would be concerned that some companies are taking too long.''
Says McDevitt: ''To a point, the more product the merrier. But licensors in the past have overdone certain things. For Batman, there were too many different T-shirt licensees. It was on every single thing and people got tired of it. Fox is much more controlled.''
Al Ovedia, Fox's vice president of product license and merchandising, said recently, ''We've turned down no less than 50 manufacturers for license because their products just weren't right.''