Last week, Sarah Killen had three Twitter followers.
This week, she has 20,000 - as well as a new iMac computer and offers to help pay for a dress and drinks for her wedding.
O'Brien decided last week to pick Killen as the only person he would follow on Twitter, turning the 19-year-old's life upside down, The Associated Press reports.
The deposed "Tonight Show" star whose exit deal with NBC barred him from TV appearances for several months, has taken to Twitter to reach the masses during his exile. But until Friday, O'Brien had steadily increased his number of Twitter devotees without following anybody else.
Enter Killen, who is finishing her high school requirements, preparing for college and getting married in September.
"I've decided to follow someone at random," O'Brien's posting read at 3:55 p.m. on Friday. "She likes peanut butter and gummy dinosaurs. Sarah Killen, your life is about to change." Boy, did it ever.
Immediately after O'Brien started following her, Killen picked up followers at a rate of 150 per minute. Then came the calls: Family, friends and interview requests.
"It's totally nuts," she said.
Until O'Brien turned Killen into an overnight Web celeb, she and fiance John Slowik Jr. lived a normal life, residing in the basement of a house more than an hour's drive west from Detroit.
The exposure has resulted in a brand-new iMac, which was bought for them by a Florida businessman.
A New York designer is donating a wedding dress, and someone else is sending wine for the nuptials.Not bad for a couple who saved $30 for the wedding, hadn't reserved a location and faced the prospect of not being able to afford a wedding dress.
"People are saying that I'm asking for gifts and stuff, and I'm not," Killen said.
What she is asking of her newfound army of Twitter followers is to contribute to charity, including the Susan G. Komen Race for the Cure.
Still, Slowik says he'd love one more thing from the man who used to make them laugh nightly during his abbreviated "Tonight Show" run.
Slowik wants O'Brien to be his best man at the wedding.
Will he do it? "I would hope so," Killen said.