Who's that girl?

She had been engaged to her boyfriend, John Slowik, Jr., for almost a year, and she was worried that they wouldn’t be able to pay for their impending wedding on Sept. 25.

She was planning to participate in the Susan G. Komen 3-Day Walk for the Cure event to raise money for breast cancer in August, and she was concerned about getting the $2,300 she needed to fundraise for that, too.

She had a new Twitter account, LovelyButton, and she had 3 followers.

And then she got a MySpace message. It was from Conan O’Brien’s camp. Yes, that Conan O’Brien. She followed the former talk show host on Twitter, and she’d always liked watching his show before he had been replaced with Jay Leno. They were asking if he could “follow” her on Twitter. Before that, O’Brien wasn’t following anyone.

She said yes, but she didn’t understand. O’Brien didn’t just want to follow her. He wanted to change her life.

In a matter of two days, Killen had some 15,000 followers on Twitter. She had 4,000 emails in her inbox on Friday night alone.

That old computer? It was replaced with a brand new iMac, for free, from a company called Hornblasters in Florida.

The wedding she didn’t think she could pay for? She had offers for someone to make her a ring, wedding invitations, for professional wedding photographers to photograph her wedding. She hasn’t accepted everything (“It feels weird taking free stuff,” she said.), but she has a custom designed dress coming from New York that she couldn’t refuse.

The money she was scared she couldn’t raise for the walk for breast cancer? She had raised the required amount in a day.

She even has a Facebook fan page dedicated to her.

She doesn’t know how long this newfound fame will last, but right now, she just wants to get some sleep and get her homework done.

“Tuesday, Wednesday and Thursday I’m completely taking off,” she said. “I’m trying to get school done. I’m not going to be online for three days. I’m so sleep deprived it’s hard to remember anything. It’s crazy.”

The pressure is on for Killen to tweet interesting things, now. She didn’t think anyone would be seeing her Twitter account, but now, thousands of eyes are on her. Besides getting offered free stuff, she’s been getting a lot of requests from people for her to promote their businesses, but for now she’s sticking to charities.

She’s encouraging people to continue donating to the breast cancer walk (some donations have come from people calling themselves “Fans of Conan and Sarah,” “Lovely Button Rocks,” and “Coco for Komen”). She’s also supporting the Children’s Hunger Fund, which was brought to her attention by the designer who’s making her dress.

As far as her relationship with O’Brien goes, she hasn’t talked to him, and she isn’t sure why he picked her or what’s going to happen. He tweeted that he had decided simply to follow a random person, and didn’t say anything about his intentions beyond, “Sarah Killen, your life is about to change.”

Killen said people are saying she should be the first guest on whatever new show he ends up hosting, and she would definitely be up for that. “I think he has a plan,” she said. “I have no idea what’s going to happen.”

Right now, she hopes to graduate and buy a house with Slowik before their wedding. She’s not sure where this will go, but she said, even if it stopped today, it was truly a life changing experience.

“It’s really all up to Conan,” she said. “He could stop it right now if he wanted to or let it go on as long as he wants to. Every time he tweets people go crazy."