After individual sets, the ‘American Idol’ trifecta come together for a cover of Gnarls Barkley’s ‘Crazy.’

The “American Idol” stars aligned Friday night (February 12), as Allison Iraheta, Adam Lambert and Kris Allen took the stage for an exclusive live event.

Ryan Seacrest’s “Rock My Town” concert brought out hundreds of lucky ticket winners, all of whom braved the cold for hours to make sure they got the best possible spot in the intimate Highline Ballroom.

Those who stayed were treated to a surprisingly loud Allen set. It smartly kicked off with his much-lauded cover of Kanye West’s “Heartless,” which has now evolved into a mash-up with the Coolio oldie “Gangsta’s Paradise.”

Later on, he played another ditty that earned him raves on “Idol,” the Swell Season’s “Falling Slowly,” except now Allen adds a few measures of U2’s “With or Without You” into the mix, making the song feel even more sweeping and emotional. So much so, in fact, that Glen Hansard stole Kris’ unique arrangement for a Swell Season show earlier this week, a tidbit Kris was eager to share with the crowd. (Allen also played his Michael Jackson week offering “Man in the Mirror” but left it untouched, presumably out of respect for MJ, whom Kris called “one of the greatest ever.”)

Allen’s been on the road the most out of the three on the bill, and it has paid off handsomely. His bandmembers sound like they have been playing together for years, and his stage presence has improved tremendously since his days on “Idol.” He no longer looks awkward when he performs without a guitar. In fact, “Can’t Stay Away,” “Written All Over My Face” and his cover of the the Beatles’ “Come Together” all showed off a newfound — dare I say it? — rock-star swagger that delighted the Kris fans bopping in the audience (even if nobody passed out, as Kris jokingly said was his goal for the night).

Even more exciting was when Allen and his band opened up the arrangements to his album songs. “Red Guitar” and “Is It Over” both approached jam-band territory at certain points, giving the 12-song set a dynamic ebb and flow.

The crowd cheered the loudest for Allen’s single “Live Like We’re Dying” (and least for the sore thumb of the night, the Pat Monahan-penned ballad “The Truth”), but the highlight was the infectious sing-along “Alright With Me.” Kris grabbed five fans out of the front of the audience to help sing backup. (A sixth “straggler” joined them.) As he helped one girl up, she suffered from “pants on the ground” syndrome, giving the crowd a nice view of her underwear. Allen, being a Southern gentleman, blushed as he stammered, “Oh gosh! Don’t … don’t look.” (It’s also important to note that Kris neglected to choose the ballsy fan who had thrown an Adam Lambert T-shirt at him earlier.)

Moments after Kris left the stage saying “Kradison thanks you,” Allen’s band returned for an encore, except this time they brought Lambert’s guitarist Monte Pittman with them. The crowd buzzed. Could it be? Would fans be treated to a one-of-a-kind collaboration?

Turns out, yes. Kris, Allison and Adam all traded verses on an electric cover of Gnarls Barkley’s “Crazy,” in an epic collaboration that played like a Rock and Roll Hall of Fame jam session: “Idol” edition. As Kris mentioned earlier in the night, “They’re my family, dude,” and that familial bond was on full display. While wailing into their mics, Adam picked up Allison, Allison draped herself on Kris, and Kris and Adam sang to each other while frenzied fans in the crowd desperately tried to keep up with their camera phones. When it all ended, the audience was in full flail mode.

If only those early exiters knew what they were missing.

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