• by Thom Forbes  @tforbes, February 15, 2012

Good morning. Quick, what sells classic American junk food best? A sizzling burger on the grill? Nope. Tempting French Fries dripping ketchup? Nah. A sumptuous hot dog bursting out of its bun? Not really.

Plain old cheesecake*; no cherry required. That’s quite evident in a forthcoming spot for two hamburger chains that share the same heritage.

“Carl’s Jr. and Hardee’s brand have always been about, you know, giving young, hungry guys what they want,” declares 72andSunny creative director Glenn Cole in YouTube’s “Behind the Scenes: Kate Upton Commercial for Carl's Jr. & Hardee's.” Then, after a montage of poses taken straight from the Marilyn Monroe playbook, climaxing with Upton suggestively biting into a oversized burger concoction, Cole avers with a full-faced smirk: “If Kate Upton is not giving young hungry guys what they want, I do not know what young, hungry guys want.”

Well, one thing’s clear besides Upton’s full figure and ample cleavage: the demographic target. The spot featuring Upton in a polka dot dress on a hill above L.A. will break late this month, Tiffany Hsu reports in the Los Angeles Times. It’s for the Southwest Patty Melt.

"It's the classic patty melt but they're adding a little spice to it with jalapeno," Upton informs us in the “making of” video. "My spice I bring to it is lingerie."

So who is Kate Upton, why does she have her own website and why is everybody -- well, 184,000 of you at any rate –- following @KateUpton?

“There was a time, not long ago, when the surest path to modeling stardom was down the runway of a top designer’s show, when it would have been unthinkable to find among the industry’s top ranks a swimsuit girl whose main claims to fame were ad campaigns for Guess jeans and Beach Bunny Swimwear,” Guy Trebay reports in a front-page New York Times story on Upton yesterday. “But that was before social media altered the paths to fame.”

The 19-year-old Upton first made her mark on YouTube last year -– a video of her “doing the Dougie” during at a Los Angeles Clippers game being the first step in her meteoric, if unconventional, rise from Florida schoolgirl to this year’s Sports Illustrated cover girl, as revealed by David Letterman on Monday night. (No, that’s not what doing the Dougie means. Join more than three million other viewers by watching her seemingly impromptu performance here.)

Trebay documents how, with a little help from IMG Models superagent Ivan Bart, who eschewed the conventional wisdom of what a contemporary model should look and act like, Upton has rocketed “to No. 2 on a list of the world’s 99 ‘top’ women” compiled by AskMen.com.

Where do you go from there? For instance, does she want to act, as Letterman asked the other night.

“I was in ‘The Three Stooges’ with the Farrelley brothers,” she told him.

“’It was so much fun,’ she said before realizing that of course David Letterman was going to have a photo,” HuffPost TV reports. “Much like her modeling work in bikinis, this picture featured Upton in a skimpy nun-inspired swimsuit alongside the Stooges themselves.

‘Which one is you?’ Letterman quipped.

(Don’t worry, you haven’t missed “The Three Stooges,” boys. It will be in a theater near you April 13, according IMDB.

If this is not enough creative excitement for the morning, check out Karl Greenberg’s report below: “Lexus Launches Curvy Swimsuit Sponsorship,” which “involves a racetrack that is intended as an elaboration of the body lines of Tori Praver,” who is also in the SI swimsuit issue.

* For an earnest discussion of the etymology of the terms cheesecake/beefcake, click here. It’s quicker than a cold shower.