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The Science Behind Wendy's Frosty & French Fry Phenomenon

Cole Saladino/Thrillist

Like the first brave soul to wrap their lips around a cow’s udder and drink milk, the culinary vanguard who broke all fast-food norms by dipping their fries in a milkshake was a crazy, brilliant bastard who changed the world by taking a chance. And he/she/it ended up with a #foodhack worthy of a thousand super-excited listicles. They broke that seal, and became an anonymous legend.

Unfortunately, there's no way to trace the phenomenon back to patient zero.

"Finding the first person to do this would pretty much be impossible," said Matt Hartings, a professor of chemistry at American University, who has a particular interest in and proclivity for the science of flavor combinations. "Really, it's a diner thing -- as soon as people started getting milkshakes and fries together, they probably started doing this."

But, it doesn't really matter. The important part is, we now know. Though superficially weird in the big-picture sense (much like having an 11-year-old redhead as the face of your brand, if you think about it), the combo of fries + shake is a modern-day alchemy of snacking majesty -- it brings all the boys, and most girls, to the yard. And there's no better ice cream to slide your spuds into than Wendy's Frosty. Its consistency is more viscous than a milkshake, but not as thick and hard (hehe) as ice cream. You can't get it through a straw -- at least not at first, so you need to have the top off.

"And why use a spoon when you can use fries, right?" Hartings said.

And he is right. Dipping your fries into your Frosty is one of the best combos in the food world, aside from actual Combos. And there's science to back it up.

You hear that -- SCIENCE. The same thing that invented light bulbs and bacteria-free cookie dough. And it's here to explain and prove why the Frosty/fry tango makes more sense than almost anything else in this crazy, mixed-up milkshake of a world.

Fry and Frosty Combination
Cole Saladino/Thrillist

"I do remember the first time I saw someone dip their fries into a Frosty," said Shelly Thobe, director of culinary innovation at Wendy's. "My roommates in college would go to Wendy's just to get fries and Frostys. In a few minutes, I went from 'never heard of it' to 'this is the best dessert ever.'" A common transition, in this arena.

As director of culinary innovation, Thobe's job revolves around experimenting with what Wendy's does, and reinventing what fast food can be. The fry/Frosty combo could easily be something that came out of that lab. But Thobe assures that this innovation is and was 100% organic.

"I don't think it is anything my predecessors imagined," she said. "It's just one of those things that people have been doing since Dave Thomas invented the Frosty. It's an underground, magic pairing that took off on its own.”

The Frosty was one of the five original items on Wendy's menu (alongside hamburgers, chili, fries, and soda). Dave Thomas -- Wendy's founder -- developed the recipe himself. He loved thick shakes as a kid and wanted a shake so thick that it required a spoon… or fries.

"The main thing we look at with this dynamic in our work is the 'Why?' Why do people love this stuff so much?" Thobe said. "And I think it's that salty-sweet, hot-cold dynamic that works so well. It's activating so many of our senses. It's taste, it's texture -- it confuses your taste buds… in a good way. It's a crazy, intense experience."

Hartings agrees.

"When you look at how chefs develop their meals, they want to strike balance of flavors, and make sure everything play well together. This is an encapsulation of that. The fries have to be crispy and hot, the Frosty has to be cold. The fries bring the savory and the Frosty brings the sweet. It's basic chemistry, really. It's how food works, and part of the reason why we love to eat."

And despite the relative oddity of this pairing, hot/cold (and obviously savory/sweet) desserts are commonplace: fried ice cream, affogato, even brownies a la mode. It's a sensation that excites the taste buds.

"And really, fries are the perfect vessels to scoop out something like this. They're porous and really soak up the Frosty quite well."

But taste is only one fraction of the appeal.

Fry and Frosty Combination
Cole Saladino/Thrillist

In Hartings' opinion the fry/Frosty appeal is just as much about culture trends as taste.

"I'm from Ohio [where Wendy's HQ is located] so I might be biased, but this is certainly something that I grew up with, I have very clear memories of doing this as a kid. Sure, there are molecular underpinnings as to why salty-sweet combos work so well, taste-wise, but the real appeal here might be something different, it's a culture thing."

Hartings thinks the social science behind this decades-long movement is just as influential as taste. When trends like this -- especially "secret menu hacks," as they may be lamely called -- steamroll into popularity, one person sees someone else doing it, and they want to do it too.

People are sheep! This is how phenomena are born. Good ideas spread like herpes in clothing-optional saunas.

Nowadays, it's just as likely that one person will see someone else tweeting about their Frosty/fry endeavors as actually doing it. According to Wendy's HQ, there are an average of 21 tweets per day about dipping fries into Frostys.

"In the digital age, this all kind of took on a life of its own on social media," said BryAnn Roth, Manager of CSR & Brand Communications for Wendy's. "But we really never used it in wide-spread marketing materials… we've never really had to. This is something people are just going to do. They've always done it. And now, they are posting about it."

"The classic diner experience really fueled this. You would order a shake. Your friend would order fries. You guys would end up sharing everything, and naturally the fries would end up in the shake," Hartings said. "Even if there's not a precedent there, it's a very natural reaction, and it's an interpersonal way to eat -- which is usually in a social setting, anyway."

So in a way, the hard science of taste (salty plus sweet!) works in conjunction with the social science of popularity and fads to create a bona fide fast-food phenomenon that's better suited to experience than explanation. You need to try it to understand.

When Thobe wears one of her company-provided shirts to the supermarket, she usually doesn't get stopped by gushing fans. When she wears her "Frosty + Fry" shirt (yes, they give those out to employees), she can barely walk 5ft without being drawn into conversation.

"Some people stop me and tell me they can't believe they haven't thought of it yet. Others stop me and tell me it's pretty much their favorite thing ever.

"No matter what, it gets a reaction, though. And that's how you know it's something special."

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Wil Fulton is a staff writer for Thrillist. He actually blames Gwyneth Paltrow for most of the world's problems. Follow him @wilfulton.