Then came the moment that would be forever known as the "Dean scream."

"And then we’re going to Washington, D.C., to take back the White House. Yaaaaaaaay."

In addition to that loud, energetic and guttural shout becoming a defining moment of the night for news programs and late-night comedy shows, denizens of the growing internet immediately turned it into mp3 remixes spliced with Lil Jon and Ozzy Osbourne’s “Crazy Train.”

The political humorists at JibJab made it a central gag in one of their early videos.

Even years later, people turned the "scream" into dance remixes, YouTube performances and famous comedy skits. Dean himself even made it a punch line in his speech at the 2016 Democratic convention.

“I look back on it with some amusement,” Dean said in an interview. “I get asked for autographs for it all the time.”

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“It is fun to have a trademark like that,” he said. “It has become iconic because it went viral.”

And the "scream" became a forerunner to the many viral political moments over the last 15 years, including:

Nicco Mele, who was the webmaster of Dean’s campaign and is now director of Harvard University’s Shorenstein Center on Media, Politics and Public Policy, argues that the entire Dean campaign — not just the scream itself — represented the first viral moment in American politics.

He says the remixes of previous Dean speeches, the online fundraising and the meet-up gatherings were all intended to get attention on the internet in those pre-Facebook days.

"It was all happening online," Mele observed.

But the "scream" was the last — and most famous — viral moment of that campaign.

"I remember being at headquarters that night," Mele said. "It didn’t look good on TV. It didn’t seem like a career-ending media event." But as it was repeated over and over, "it played into a long-running media narrative about Dean’s intensity — a media narrative that many of us never felt was very fair," Mele observed.

He added, "It landed on fertile ground."

Perception of the "scream" versus reality

Beyond its viral nature, there was another important story behind the moment: It played much differently to those in attendance in that Iowa ballroom 15 years ago — including this reporter —than to those who saw it on television.

The reason was that the microphone for the TV cameras (and the TV audience) drowned out the rambunctious crowd who cheered on Dean, despite his disappointing third-place finish.

"I remember the crowd was very into it, very loud. And because of that, it really didn’t seem that odd. More like a weird little cheer he improvised to try to match the intensity of his audience," said CNBC anchor Carl Quintanilla, who was NBC’s correspondent covering the Dean campaign in 2004.

"My most vivid memory is then getting to a computer and pulling up Drudge," Quintanilla continued, referring to the conservative website. “I’ll never forget, the banner was: 'DEAN GOES NUTS' — with a picture of him mid-scream."

"The scream itself didn't catch my attention, per se, both because it wasn't entirely out of character and because it mirrored the mood in the room," added Felix Schein, who was NBC’s embed reporter covering the campaign.

"In the room, you couldn’t hear a damn thing," said Tricia Enright, Dean’s communications director in 2004, referring to the crowd in the ballroom. "It wasn’t until the playback that, ‘Oh my god, this is bad."

And there’s the misperception that the "scream" — rather than Dean’s third-place finish — doomed the campaign.

"We took third that day," said Joe Trippi, who was Dean’s campaign manager. "We had three weeks of gaffes and mistakes that caused us to take third."

"What did in our candidacy was ourselves," Dean told NBC News.

But Trippi says the scream is a lesson for future political candidates when making a victory or concession speech after the first nominating contests: focus on the TV audience.

"It’s actually the first time that most of America is looking at the candidate," he said. "Don’t talk to the room. Talk to those people."