When Brooke Carter, a teenager in Murrieta, Calif., woke up this morning she had no idea she'd be swept off her feet on live television in a prom-proposal surprise.

Her good friend Britton Phillips was visiting New York City on a trip with his choir group when he decided to drop by the "Good Morning America" studios. Standing outside in Times Square among the rest of the crowd, he proudly held up a large, cardboard sign that read "Brooke Carter PROM!!!."

Carter, 17, had been warned the night before by another friend, who was also in New York with Phillips, to make sure to watch "GMA" this morning because she was going to be on the news.

"My friend … said to record 'Good Morning America' because she was going to be on it, so she had an excuse for me to be watching," Carter told ABCNews.com.

But it wasn't until Phillips made his way into the " 'GMA" studios to be on set for "GMA LIVE!" that the real surprise happened. He approached the anchor desk to ask that ever-important high school question:

"Brooke, will you go to prom with me?" Phillips said into the microphone.

"Oh my God. Yes!" Carter immediately responded over a live phone interview.

The audience instantly started cheering, congratulating the new prom couple.

"Nice job. That is amazing," Josh Elliot said.

"Holy crap," Carter said after the surprise had ended. "I was shaking like crazy, and I had to wake up my mom. And my mom was like, 'Oh my gosh.' She recorded me with the iPhone. My dog was all excited because I was so excited."

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Carter explained she and Phillips were not boyfriend and girlfriend but know each other from church and were very good friends.

"He goes to a different school, so I don't really know when his prom is," Carter explained. "But I already have a dress. Another friend had asked me, but he said he's not going to go with me anymore."

Fortunately for Carter, she has a brand new date, and quite the story to tell all her friends at school.

"I already told them, and they're just totally speechless," Carter said. "This was the craziest thing that's ever happened to me."