Keenan Cahill's an Internet star, for now

ELMHURST, Ill. -- It started innocently enough, with a boy hamming it up in front of a computer webcam.

He was doing what teens often do when they stand in front of mirrors: Lip-synching to a popular song, acting goofy, being himself, as if the world wasn't watching.

Except, in this case, the world was watching when Keenan Cahill -- then an impish 13-year-old with a knack for oddball humor -- started posting videos of himself on YouTube. First, there were hundreds of hits, then thousands, then millions. And an Internet sensation was born.

"Keenan, what have you done?" his mom asked when a late-night talk show called and wanted to air one of his lip-synching videos.

She wasn't sure how to react: What if people made fun of her son, who has a rare genetic disease that has stunted his growth? What if he'd opened the door to something too big to handle?

For Keenan, though, this was the adventure he'd been waiting for. This was freedom for a young man whose life had, so far, mainly consisted of spending time at hospitals, when he wasn't going to school or hanging out in his room. For him, a vacation was going to Minnesota to a children's hospital, where he's had several surgeries on his legs and hips.

Now he gets to travel to places like the Bahamas and France, Los Angeles and Las Vegas. Fans crowd around him as if he were a rock star, their cellphones extended to capture photos and video.

"I finally got somewhere, out of all the people," says Keenan, who's now 16. "I used to pray to God. It's like a switch-back now. I say 'Thank you' instead of, 'Can you please get me there?' "Some have compared Keenan to Gary Coleman, the late actor whose growth was stunted by a kidney disease. But people most often stop to tell him that he looks like the young actor from the movie "Jerry Maguire."

Some might not believe this can really happen to some kid who shoots low-budget videos in his bedroom. But one only need observe the fervor with which people try to contact him to understand that this phenomenon is, indeed, real.

"It's completely redefined the definition of celebrity," says Victor Mehren, a senior marketing director at the Wrigley Co., which hired Cahill to appear in an online ad for Juicy Fruit gum.

He's helped open a teen club in the Bahamas. He's shot a commercial with actress Jennifer Aniston, which has gotten more than 8 million hits. He's done videos with rapper 50 Cent and "Jersey Shore" star DJ Pauly D, among others.

"It's insanity," his mom says, "but a good insanity."