A generation of young Americans slammed the door Monday on the great big boogeyman of their childhoods with an epic woot-woot and rounds and rounds of “U.S.A.!”

At the news of Osama bin Laden’s death, thousands of people — most of them college-age and in requisite flip-floppy collegiate gear — whipped up a raucous celebration right outside the White House gates that was one part Mardi Gras and two parts Bon Jovi concert.

There were cigars, a few beers, a lacrosse-stick-turned-flagpole waved by a kid who just climbed a statue, joining others aloft in trees and atop lampposts. Well past midnight, cars zipped up and down the streets of downtown Washington with women standing up through sunroofs waving ginormous American flags and guys blowing vuvuzelas, spring break style.

It felt a little crazy, a bit much. Almost vulgar.

Because meanwhile, across the river, at the Pentagon, in the ghostly quiet of lights at the Sept. 11 memorial, a military veteran silently wept.

And many others cried, too, sickened by the death toll, the enormity of almost 10 years of fear, death and terror.

The death of bin Laden will be a grief-tinged, complicated event for many Americans. I immediately saw the mixed reactions of my peers on Twitter and Facebook. Folks who lost close friends or family in the Sept. 11 attacks orchestrated by bin Laden or the war on error that followed had a rush of new emotions and raw pain at the news of even more bloodshed.

Is it over? Everything better now that they got him? Not really.

When I saw that folks were celebrating in the streets at the news of bin Laden’s death, my first reaction was a cringe. Remember how we all felt watching videos of Muslims dancing in celebration on Sept. 11, 2001?

Are we simply creating star-spangled recruitment tapes for a new generation of terrorists killing in the name of their new martyr?

So a jacket went over my pajamas, shoes went on my feet and off I went to see the macabre jubilee downtown.

One of the first people I met was Mohsen Farshneshani, who was fist-pumping in a U.S.A. chant amid a huge crush of college kids.

“When 9/11 happened, I was in fourth grade. It changed everything,” said Farshneshani, a 19-year-old freshman at the University of Maryland. “The way people treated me, my family, the mean things everyone began saying to us.”

A Muslim who grew up in Olney, Farshneshani watched his religion get hijacked by the man he often blamed it all on: bin Laden.

He remembers a “perfect” life in third grade, when he had non-Muslim friends and it seemed as though no one cared that he practiced a different faith.

After bin Laden’s attacks, there was a seismic shift. The kids still willing to come on play dates were suddenly accompanied by their parents. At his birthday party, he watched parents sneak around the house, poking their heads into different rooms, looking, presumably, for those suspicious signs of terrorist activity the government — via highway signs and billboards — repeatedly asked us all to report.

So in the wee hours of Monday morning, with the biggest boogeyman of his young life gone, Farshneshani felt like everything might change.

“This is a new opportunity for Muslims, and a great victory,” Farshneshani said.

He’s part of a color-coded terror alert generation, the kids who open their backpacks at museums and libraries and take off their shoes at airports without being asked because that’s what you do, right?

Their daily news has been body counts and deployments. Their Halloween candy goes to soldiers; their fundraisers are for injured veterans. They are the ones who saw, way earlier than any child should, their parents cry and freak and crumble on that day in September 2001.

For Sarah Powers, 19, the specter of Osama bin Laden as ultimate bad guy was there for her entire young life.

“I remember sitting in the classroom, watching the TV that day, 9/11, and how scared everyone was,” said Powers, a freshman at George Mason University. “We grew up with war. That’s most of what we know, being in a country that’s at war. To be here tonight, when they got him. Wow.”

Yes, they deserve a night of wow, a confetti-in-the-streets moment of victory, a V-Day.

Because after this, it’s probably going to stay very, very complicated.