It can only be called the Afro-Americanization of Bart Simpson.

Young black folks across the country have adopted the wisecracking lad from "The Simpsons" -- that wildly popular cartoon satire of white middle-class family life -- as one of their own. At least when it comes to bootleg T-shirts.

At sidewalk stands everywhere, there is Bart wearing Nikes and sweat pants, Bart with a thick gold chain around his neck, Bart dancing to a beat box, Bart with cool "tracks" shaved across the side of his head.

And whether his skin is a naturalistic brown or a phosphorescent green, he's often uttering lines from hit rap songs. "Big ole butt!" "The girls, the girls they love me..." "Do the Humpty-Hump!" "You say he's just a friend."

Then there's "Air Simpson" -- Bart shattering a backboard with a behind-the-back slam dunk, his tongue hanging out like Michael Jordan's.

One eyewitness tells of a hot new black Bart T-shirt on the streets of New York City: South African leader Nelson Mandela is standing over Bart, who's saying, "He's my hero."

A 14-year-old youngster selling boxes of candy in Union Station explains his ownership of seven Bart Simpson T-shirts with a simple declaration: "He's funny." The shirt he's wearing this day features a vulgar illustration of Bart with a comically obese black woman.

Don't ask Sebrina Warren of Northeast to explain it, either. After buying a T-shirt for her 4-year-old son, Michael -- the shirt with Bart and a Teenage Mutant Ninja Turtle shaking hands, and the message "Friends won't let you down," taken from a Jody Watley song -- she says, "He likes Bart. Everywhere I go, it's 'Bart!' "

Even the vendors can't figure it out. "I'll be honest with you," says the man running a stand on Rhode Island Avenue in Northeast. "I don't know why in the hell people like 'em. But why not?" On a bad day, says the vendor, who wouldn't give his name, he'll sell 25 T-shirts at $6 or $8 apiece, most of them Bart-related.

The only street phenomenon similar to this, in recent memory, was the bootleg, Afro-Americanized Mickey and Minnie Mouse T-shirts of a few years ago ("Yo baby, yo baby, yo ..."). But that was peanuts compared with the unmitigated appropriation of Bart Simpson.

"He's rebellious, he's cool," says Bill Stephney, president of SOUL: Sound of Urban Listeners, a New York record label. Bart, in fact, is "probably a lot more rebellious than a lot of the rappers today," he says. "He's certainly to the left of Young M.C. and M.C. Hammer." (Rap fans will hear an allusion to Bart Simpson in the song "Kelly Bundy" -- inspired by another Fox network hit, "Married ... With Children" -- by one of Stephney's groups, Young Black Teenagers, before the summer is over.)

Harry Allen, music writer and avowed "hip-hop activist," as well as a publicist for the rap group Public Enemy, says, "I think the Bart character is appealing because -- I don't want to say he's kind of black. I don't mean that. He's just got some very unusual characteristics, from his haircut to his use of the word 'homeboy' infrequently, to even his general sassiness." (On "The Simpsons," Bart has also used the funky phrase "work that body.")

Allen is a regular watcher of "The Simpsons" -- it's "the most attention I give white people during the course of a week," says this avid Afro-centrist -- and the show's "lack of pretension just resonates in general with the way black people view the world," he says.

What does "Simpsons" creator Matt Groening have to say about Bart's iconic significance to young African Americans?

"I can't decide whether it's that Bart lives up to their stereotypes of how stupid whites are," Groening says by phone from Los Angeles, "or whether they know the secret truth -- that Bart is black himself."

Say what?!

He's kidding about Bart's ancestry. But Groening does say that the affinity between Bart Simpson and black youth is mutual. "I know the character better than anybody, and I know that Bart likes hip-hop," he says. Groening is actually writing a rap song for Bart right now, part of an album to be called "The Simpsons Sing the Blues," which should be released this fall.

On the West Coast, Groening has seen an unauthorized T-shirt combining Bart Simpson and Magic Johnson, and a "reggae" T-shirt that drapes the whole Simpson clan in dreadlocks.

While he is "flattered" by the street response to "The Simpsons," "I must say I have mixed feelings. You have to have mixed feelings when you're getting ripped off," Groening says. "I don't like these smokestack factories belching out bootleg Simpsons T-shirts. It's a huge business. 20th Century Fox takes this matter extremely seriously. There have been busts all over the country."

Still, he says, "the creativity of the way people respond to the show is fantastic. You should see the fan mail. Kids send in their pictures of Bart beating up other cartoon characters."