LOS ANGELES (AP) -- If you haven't heard of him yet, Fred Figglehorn likes to say, you're probably really old or something.

And Fred, with his nerdy striped shirts and that high-pitched, sometimes annoying voice that falls somewhere between the sound of fingernails scratching a chalkboard and Pee-wee Herman on steroids, is probably right.

But if your age falls just south of 18, and like most teens you spend your social life on a computer, then Fred is about the hottest thing to come along since Justin Bieber.

Fourteen-year-old girls want to hug him. Kid-centric clothing outlets sell his goofy T-shirts. Fans have clicked on his YouTube channel more than 500 million times.

Now Fred, the creation of an amiable, unassuming high school junior from Nebraska named Lucas Cruikshank, is about to be unleashed on the general public (meaning all of us "really old" people).

"Fred: The Movie," a 90-minute, big-budget expansion of the brief webisodes Cruikshank has been producing in his bedroom the past four years, makes its debut on the Nickelodeon cable network on Saturday at 8 p.m. EDT.

It's not the first attempt to expand an Internet phenomenon into mainstream media. The popular Internet duo Ryan Higa and Sean Fujiyoshi were also discovered on YouTube a couple years ago and the result was the 2008 film "Ryan and Sean's Not So Excellent Adventure." It grabbed little attention, however, earning just two reviews on the movie website rottentomatoes.com. One dismissed it as "excruciatingly unfunny" while the other called it "worse than sophomoric."

Nickelodeon is expecting "Fred" to fare much better.

For one thing, if you can handle that Urkel-on-speed voice, Cruikshank is actually very funny.

"He's got this very inner-type awkward nerdy thing that's really in right now," says Jennette McCurdy, the 18-year-old actress who plays Fred's best friend, Bertha. "He's got that, but at the same time he has something that's just so kind of offbeat and quirky that I think it really sucks people in."

And, unlike most popular Internet webcasts that feature either song parodies, takeoffs on movies or people just doing stupid things, Cruikshank's show has an established back story and fully formed characters, including a loving but certifiably crazy father and a quirky but loyal best friend in Bertha. Then there's Judy, the beautiful, popular girl who, unknown to her, is the love of Fred's life.

Always off-camera in the web series, the characters are played to great comic effect in the film by professional wrestler John Cena, McCurdy and British pop star Pixie Lott.

"What Lucas has done, which no other kid has really done and even many adults have not been able to do, is establish a brand new character that has resonated with people for more than just one shot," says Marjorie Cohn, president of development and original programming for Nickelodeon and MTV's kids and family group.

Cruikshank, for his part, says all he set out to do was put a few videos on the Web poking fun at the ones that seemed to feature nothing more than some anonymous soul pouring his heart out.

Although he'd wanted to be an actor and writer for as long as he could remember, he never really expected many people would watch them. In fact, he says, he hardly told anyone what he was doing.

"Because it just kind of sounds weird," says Cruikshank, who unlike Fred is very soft-spoken.

He was more than a little taken aback when people started showing up in his small rural town 90 minutes outside of Omaha to ring the doorbell and ask to meet Fred.

As a result, he is reluctant to reveal too much about himself these days, although he volunteers his mother is a nurse and his father is "an executive person or something at this plant in my town." He is the fourth of eight children.

"He's got a jillion brothers and sisters so he just has a very grounded personality," says McCurdy, who co-stars in the hit kids TV show 'iCarly."

"He's not Hollywood at all," she adds, meaning that in a good way.

But Cruikshank, who turned 17 last month, says he may have to move to Hollywood soon. He recently signed a deal to develop a TV series with Nickelodeon. He won't be playing Fred but another oddball, a kid who doesn't let on to his classmates that he's really from Outer Space.

Until then, though, he'll concentrate on his schoolwork in Nebraska. He's studying algebra, chemistry, Spanish, journalism and drama.

"Pretty exciting, huh?" he adds with a laugh.