Viral marketing has become a hip, low-cost way to reach a lot of people very quickly — with little effort. But as marketers, including giants such as Anheuser-Busch, Coca-Cola, and Procter & Gamble, slash ad budgets, “viral” needs to mean more than “free” and “fueled by prayer.” Making an idea contagious isn’t a mysterious marketing art. It boils down to a couple of simple rules.

Why is the gang-initiation tale so irresistible to pass on? Notice a few things about the idea. It’s emotional — in fact, if you believe it, it’s terrifying. The French psychologist Bernard Rimé has found that people almost compulsively share emotional experiences (both positive and negative), and the more intense the emotion, the more likely they are to talk about it.

There’s another emotional angle: When someone shares this legend with you, they feel like they’re doing a public service. They might believe they’re saving your life. And that’s the second trait of viral ideas. It’s often a small favor: “Hey, it’s Free Breakfast Day at Denny’s!” or “Dude, have you seen the video of that David kid who was drugged up after his dentist visit?” It feels good to save our friends money, or delight them with nitrous-oxide humor.

Fortunately, the rules also work for normal ideas. In Emanuel Rosen’s recent book, The Anatomy of Buzz Revisited, a must-read for marketers, he talks about the National Outdoor Leadership School. One of its alumni, Amy Rathke, returned to Willamette University, where she was an undergrad, raving about her time at NOLS. She had climbed rocky canyons and camped on beaches. It was an emotional experience, and by telling her friends, she felt she was doing them a favor because they could enroll next year.

Rathke talked a lot about her experience when she first returned, and as time went by, she naturally talked about it less and less. A year later, though, Rathke’s conversations about NOLS suddenly spiked again.

Why? Because NOLS promotes its outdoor leadership classes by driving through college campuses in a bus. It’s no ordinary bus. It is wallpapered with photos of the graduates’ adventures and, in keeping with the environmental theme of the program, runs on recycled vegetable oil. When the bus comes to town, NOLS graduates are contacted and given a mission: help find enough used oil to keep the bus moving.

Rosen calls this a “trigger,” and it’s the third trait of a viral idea. A trigger is an environmental reminder to talk about an idea. For instance, a golf tournament is an excuse to trot out your public-service info about the state of Tiger’s knee, and a cup of coffee reminds you to talk about Starbucks’s no-decaf-after-noon policy. When the bus rolled into town, Rathke had a trigger to start talking up her NOLS experience again. She persuaded all of her friends to go check out the bus that runs on french-fry oil.

If you want people to talk about your product or service, you need to ratchet up one of these three traits. Consider a 360-year-old Finnish company named Fiskars, which makes orange-handled scissors. If ever there was a viral-marketing challenge, it’s scissors — a product with all the sizzle of a RAM upgrade. Brains on Fire, a brand-identity firm based in South Carolina, helped Fiskars find the emotion. “We knew we had to move from a product conversation to a passion conversation,” said Spike Jones, the firm’s “firestarter.” Jones and his colleagues realized there was one community that was indeed passionate about scissors: arts and crafters. They found four arts-and-crafts zealots and christened them “Fiskateers.” Then Brains on Fire asked the Fiskateers to select additional compadres who would support other people in their crafting hobby. (Notice the added public-service element.) Since the project launched, there has been a 600% increase in online mentions of the Fiskars brand.

Evian Roller Babies international version:

Bare essentials of safety from Air New Zealand:

Cadbury Eyebrows (official version):

Office 2010: The Movie

Part of the above article is from FastCompany.com