The aisles of Madison Square Garden teem with tweenyboppers whose screeching and dancing is starting to give way to whining and fidgeting. They have, for the past two hours, endured Hilary Duff, Michelle Branch, Jason Mraz, 3 Doors Down, Kelly Clarkson, and matchbox twenty at Jingle Ball, the annual mega-concert thrown by New York radio station Z100. Now it's creeping toward 9 p.m. -- like any pop marathon show, Jingle Ball is running behind schedule -- and some of the crowd is getting cranky. It is, after all, a school night.
Meanwhile, Nick Lachey and Jessica Simpson are backstage preparing for separate 15-minute sets. But just before their back-to-back appearances, there's a last-minute change: Could the couple combine their two sets into one? And maybe sing a Christmas carol? ''We thought it'd be fun for us, being newly married, to sing at Madison Square Garden,'' says Simpson. And it just so happens they've got this great a cappella version of ''O Holy Night'' they've been practicing.
Within minutes, the announcer introduces ''Jessica Simpson and Nick Lachey'' while brief shots from MTV's ''Newlyweds'' play on a giant video screen. Simpson makes her entrance and asks the crowd to welcome her ''beautiful and amazing husband.'' The duo sing his and hers singles (Nick's ''This I Swear'' and Jessica's ''With You'') and launch into the Christmas carol, but not before Simpson tells the audience: ''We worked on this next song in the shower, so it's real good.''
Yep, it seems everyone is happier when Nick and Jessica are served up as a package deal. After years of existing on the fringe of celebrity with moderately successful pop-music careers, Lachey and Simpson have finally found fame in the most unexpected place: by turning their fledgling marriage into a reality TV spectacle. Since debuting in August, ''Newlyweds: Nick & Jessica'' has supplanted ''The Osbournes'' as MTV's most talked-about domestic-train-wreck series, thanks to a bubbly mix of opposites-attract antics (he's neat! she's a slob!), Simpson's out-of-the-mouths-of-blondes brilliance (''Twenty-three is old. It's almost 25, which is almost mid-20s''), and genuine sitcom-couple chemistry. Pulling in 2.7 million viewers a week, ''Newlyweds,'' which begins its second season Jan. 21, has also ushered in a subset of the schadenfreude-fueled reality TV genre -- call it ''Lifestyles of the Rich and Clueless'' (see Ally Hilfiger, Paris Hilton, etc.).
Most importantly for Simpson and Lachey, however, the series has given them a sustained stay in the spotlight -- something they've yet to achieve through their musical talents. Lachey, 30, will take his fame where he can get it: ''What's cool is our success on the show is from us being us.'' Adds the 23-year-old Simpson: ''For so long in the stupid teen-pop culture, everybody was like, 'All your fans have to envision themselves with you and believe that they can be the one.' Everybody from my record label to my father as my manager was like, 'Don't get married.' But when I got married, my career began.''