When Nina Bargiel was 27, she scored an invite that most girls would've squealed over in the early 2000s: an invite to Aaron Carter's 13th birthday party. As writers for Lizzie McGuire, Bargiel and her brother, Jeremy, were on a mission to get Carter on an episode of Disney Channel's hit series starring Hilary Duff.

"We were told, 'We want Aaron Carter on an episode. Go to his 13th birthday party, find him, and talk to him,'" Bargiel told MTV News over the phone. "I was like, I'm a 27-year-old woman, I'm not going to, like, a 13-year-old's birthday party, but turns out, that's just what they had you do. And it was held at Bergamot Station, which is like art galleries and stuff, but there was alcohol there, so I was like, OK, I'm here for this party."

From 2000 to 2002, Bargiel penned 17 episodes of Lizzie, including the unforgettable "Here Comes Aaron Carter" holiday special, titled "Aaron Carter's Coming to Town" in the original script. In it, the "I Want Candy" singer filmed a Christmas-themed music video in the McGuires' hometown, and — thanks to some strategically placed mistletoe — Lizzie got to meet AND kiss her celebrity crush. (At the time, he was quite likely your crush, too.)

This smooch was a Very Big Deal for fans, because Disney Channel rarely aired mouth-to-mouth action. Bargiel decided "Here Comes Aaron Carter" would be the exception, all because of that fateful birthday party.

"So Hilary is just like smitten with Aaron ... he's kind of acting like he does not know that she exists," Bargiel recalled, "and so the night ends, it's like, yes, Aaron's going to do the [episode], and Hilary is just like, 'Oh my god, he's so cute.'"

So Bargiel put on her matchmaker hat and wrote mistletoe into the script. "That's the only way I could get them to kiss. I feel like it would have been weird otherwise," she said, later adding, "If she had come to me and said, 'I'm not OK with this,' it would have been gone."

Turns out, mistletoe randomly hanging in a pop star's doorway wasn't the most surprising event on set. As Bargiel remembers it, when Carter showed up, he still didn't know who Duff was. (Please imagine Kate Sanders making the L-shaped "loser" sign with her fingers at this moment.)

"Aaron is in makeup, and Hilary walks in, and he says, 'Hey, there's the girl from the party.' He didn't realize it was her show," Bargiel revealed.

Of course, that changed soon enough. Carter and Duff's fictional mistletoe meet-cute kicked off their real-life romance. For nearly two years, their relationship captivated fans and tabloids alike. Think of them as the Jelena (Justin Bieber and Selena Gomez) of the early '00s.

But things got complicated when Lindsay Lohan entered the picture. At some point, Carter dated LiLo, and rumors swirled about a feud going down between her and Duff. Everyone involved has since moved on with their lives, but in 2003, this love triangle, too, was a Very Big Deal, and Bargiel still wonders what role her mistletoe played.

"Maybe if they didn’t have them kiss, that wouldn’t have happened," she said. "So I kind of personally hold myself responsible for the whole thing."

In fact, around one year into his relationship with Duff, Carter was supposed to star on a second Lizzie episode. A week or so before the shoot, he bailed on "Welcome Back Carter," Bargiel said, due to pressing obligations for Seussical the musical. (2002 was a wild time.) Frankie Muniz, playing himself, stepped in instead, because Lizzie was exceptionally lucky in the meeting celebrities department.

Over 15 years later, Bargiel's still writing for children's television, both live-action and, most recently, the animated series Barbie: Dreamhouse Adventures. She's also an on-screen contributor for Cozi TV's 10 Secret Stories, but could anything ever really beat her cameo as Hottie No. 2 in "Here Comes Aaron Carter"?

"The thing that I'm sort of seeing more with kids' TV is that ... [episodes] are built around, like, let's be as loud as we can," Bargiel explained. "Everything felt like, OK, we're going to end up in this human hamster wheel. And so then you'd always work backwards from the hamster wheel as opposed to starting with a problem that feels very real and [there's] conflict. ... In the Christmas episode, that episode was the first episode that I think I've ever written where I started from the mistletoe and worked backwards, because I was just like, there has to be mistletoe. The first question I asked our executive producers was, can it be a Christmas episode?"

And now, every holiday season, fans fondly rewatch Carter's "I Want Candy" music video and remember the Disney Channel kiss that made their third-grade hearts flutter.