The Best Word of Mouth Marketing-Nir&Far
11 Dec 2025 · 6 min
This is a podcast episode from Nir Eyal's Near & Far series featuring Jonah Berger (Wharton marketing professor and author of Why Things Catch On). Berger explains the role of "triggers" as one of six principles that make ideas and products contagious, using examples such as Geico's "Hump Day" ad (weekly spikes in shares tied to Wednesday triggers) and Hershey's linking Kit Kat to coffee (sales rose ~40% in 12 months). The episode frames word-of-mouth as a predictable, science-backed process marketers can apply to make products more top-of-mind and shareable.
Questions this episode answers
September 17, 2018
Jonah Berger, marketing professor at the Wharton School (author of Why Things Catch On)
Over 20 million times
Sales increased almost 40% (over a 12-month period)
Chapters
Hi, I'm Nir Eyal and this is the near and Far Podcast. This podcast is about business, behavior and the brain. On this show, I do a few things. I read quick articles I've written about topics shaping your behavior. I interview authors of books I enjoy, and from time to time I devote episodes to answering your questions. If you want to ask me a question, visit the podcast page on itunes, go to Ratings and Reviews and ask me a question by leaving a review. I promise to read it and possibly include your question in a future episode. So please ask me anything now. Enjoy the episode. And for more, you can always Visit me@nearandfar.com.
What triggers the best Word of mouth? Marketing by nearandfar.com.
Jonah Berger is a marketing professor at the Wharton School and and author of the New York Times best seller why Things Catch On Contagious explains the science behind word of mouth how six key factors drive products and ideas to become popular, and how you can apply that science to get your own stuff to catch on. Whether you run a small business or work for a large one, and whether you sell a product or offer a service, everyone wants their stuff to catch on. More users, more sales, and more growth. But why do some products and ideas become popular while others fail? And how can we harness that science to make our own products and services more popular? One of the most shared campaigns of 2013 was Geico's Hump Day ad. It stars an annoying camel walking through a crowded office, interrupting people. Guess what day it is? He bellows. People roll their eyes and try to ignore him, but he persists. Julie, hey, guess what day it is. Aw, come on. I know you can hear me. Finally, he finds someone who responds. It's Hump Day, she says.
Woot, woot.
Yells the camel. How happy are folks who save hundreds of dollars switching to Geico, a voice intones. Happier than a camel on Wednesday. The ad is funny, but it's not that funny. And Geico didn't spend more money showing this ad than its others. So why was the ad so successful? Why did over 20 million people share it? One clue comes from analyzing the temporal pattern of share data. If you look at the number of people sharing Geico's Hump Day ad over time, you'll notice an interesting pattern. There is a spike in shares, and then it goes down. Then another spike, and it goes down. And so on again and again. Look closer, though, and you'll notice that the spikes are not random. In fact, they're exactly seven days apart. And if you look even closer you'll notice that they're always on the same day of the week that day, Wednesday, or as it is colloquially known, Hump Day. Geico's ad is equally bad or good, depending on your preferences. Every day of the week I've checked, it's good or bad on Monday, good or bad on Tuesday, good or bad on Wednesday, etc. But Wednesday provides a ready reminder what psychologists would call a trigger to make people think about and talk about the Geico ad. Because if something is top of mind, it's much more likely to be tip of tongue.
The Power of Word of Mouth Marketing Word of mouth advertising drives all sorts of products and ideas to catch on. It's 10 times more effective than traditional advertising and shapes everything from the products people buy to the services they use. But why do people talk about some things rather than others? It may seem random, but just chance that one product or app or service gets more buzz than another. But it's not, as I talk about in Contagious why things catch on. Six key factors, or what I call steps, drive all sorts of products and ideas to become popular. Take triggers. If someone said cats and you might immediately think of, well, dogs. If someone said peanut butter and you might immediately think of jelly. Peanut butter is like a little advertisement for jelly. Seeing, hearing, or even thinking about peanut butter makes people think about its frequent partner, jelly. And because triggers make things top of mind, they also shape what we talk about and how we behave. Hershey's effectively used triggers to help reinvigorate the Kit Kat brand. Sales were down and Hershey's needed to get people thinking about KitKat again, so they started linking KitKat to coffee. Taking a coffee break. Have a Kit Kat Thinking about coffee. Think about Kit Kat. Kit Kat and coffee. Coffee and KitKat. Best friends forever. 12 months later, sales were up almost 40%. Why? Because linking KitKat to coffee helped remind people of the brand. And coffee was a great trigger because many people drink coffee frequently, multiple times a day, making it more likely that they would think of KitKat frequently as well.
What's your peanut butter? What's the thing in the environment that will remind people of your product, service or idea, even if you're not around? Because you can spend a lot of marketing dollars trying to remind people you exist. Or you can link yourself to a trigger and the environment will do the reminding for you. Every time people see that peanut butter, they'll think of you. Generating good word of mouth or getting your product or advertising to go viral sometimes seems like magic, like catching lightning in a bottle. But it's not. There's a science behind it. Triggers are only one of the six key principles that drives all sorts of things to catch on, including word of mouth marketing ideas. Understand that science and you can make your own products and ideas more contagious.
This guest post was authored by Jonah Berger, the author of the New York Times bestseller why Things Catch On.
Thanks for listening to this episode of the near and Far Podcast. You can always find more at my blog, nearandfar.com and don't forget, if you have a question you'd like me to explore in a future episode, leave me your question. The former review for the podcast on itunes.