A few songs into fun.’s headlining set at the Wiltern, lead singer Nate Ruess paused, and cracked a smile–the same wide, giddy smile that every member of the audience had worn to match. “Tonight is a special night,” he said. Then, after a moment, “Sorry, I just thought about stuff in a sexual manner. Tonight is a special night for both of us, right?”

Right.

After an enjoyable opening by rambunctious electropop vixen Charli XCX, fun. claimed the stage for an hour and a half of incendiary joy. They began “One Foot,” in a full blackout, and from the moment the lights popped on, six musicians had two thousand Angelenos in the palm of their hands. The lightshow, done by the excellent Jackie Finney, was actually emotional–dancing in tandem with the band as they played their guts out.

Both the founding and touring members are great performers, and although the greaser-chic look they sport might hint at some indie snobbery, this band is genuine and absolutely sincere. Emily Moore on keys, backup vox and acoustic guitar adds an extra kick of cool, and Andrew Dost is a wicked switch hitter, rocking everything from an upright piano to a trumpet. Jack Antonoff and Nate Harold (on guitar and bass, respectively) keep the pace with their own exciting performances–dancing and jumping and rocking it out–but it’s Ruess’ limitless voice and inertia that puts the whole show on another level. He earns every ounce of the crowd’s affection, leaping madly from one end of the stage to the next, conducting singalongs, and belting his face off.

After winding their way through the bulk of their latest record Some Nights, the band stripped down to its’ three-piece foundation. Jack dedicated “The Gambler” from 2010’s Aim and Ignite to Andrew’s parents, celebrating their 33^rd anniversary on this very night. (As luck would have it, this reviewer happened to be standing right beside the couple, who clasped hands as their son and his band played this song about lifelong commitment with the whole room singing along.) The rest of the band returned to stage for the soon-to-be third Some Nights single, “Carry On,” a song in their signature motif; an epic call for courage. Perhaps it is the passion inherent in marching anthems like these that inspired the crowd to get so utterly on board–in a town that is typically so over it all. No matter the cause, it was impossible to deny the feeling that there was something momentous about this night.

During “Take Your Time,” Ruess sang “I’m just a boy inside a voice,” then took a dramatic pause which the audience happily saturated with screams. The affection in the theatre was tangible. “You’re too good, you’re too good,” he told us. “I hate to say it, but I love Los Angeles.” Then the hits rained down along with showers of confetti and balloons, concluding “Some Nights” with a room gone wild pogoing, laughing and roaring approval.

All in all, this band’s name ain’t no exaggeration. They are pure fun.