For the most part, becoming a multimillionaire takes a lot of hard work and is usually preceded by several failed business plans. But sometimes you get lucky.

It might be a quirky idea that strikes as you drift off to sleep or one that hits during a chat with friends, but if the stars align just right, that idea comes at just the right moment, latching on to the zeitgeist of the time and emerging into a phenomenon.

Oftentimes, the very same ideas that were big pop-culture hits quickly become objects of ridicule. But by then, the inventors have laughed their way to the bank, and though sales slow, they often don't die entirely.

Here are 10 people whose ideas may not have seemed destined to become multimillion-dollar products but beat the odds nonetheless.

—By Chris Morris, special to CNBC.com
Posted 19 September 2015

Dahl, a California advertising executive, was one of the original unlikely millionaires, convincing more than 1.5 million people in the cash-strapped mid-1970s to spend $4 (over $18 in today's economy) on a rock.

The idea was born as Dahl and friends discussed the inconveniences of living, breathing pets, who required food, grooming and/or pooper scoopers/litter boxes. Rocks, he decided, were the perfect pet.

Once he packaged them in a small carrier case with a guide to training and caring for the rock (sample instruction: "If you are getting blood out of your rock, you should contact the Internal Revenue Service immediately. They've been attempting to do this very thing for years."), the money started rolling in.

Where is he now? Dahl passed away in March of this year at the age of 78.

Credit Pellettieri's wife with the now iconic singing seafood. As the couple passed by a fishing store, the inspiration struck her. And two years later the product was on shelves. (Joe Pellettieri at the time was vice president of product development for Gemmy Industries, a Texan novelty outlet, which distributed the original product. It never released specific sales figures for the product, but the company has said it sold "millions and millions and millions.")

Imitators soon flooded the market, but the singing fish was the defining gag gift of the late '90s and early 2000s. It even made it into a McDonald's commercial.

Where is he now? Pellettieri left Gemmy in 2010 and is currently vice president of product development for Occasions, a division of Manley Toy, where he continues to conceptualize and develop new seasonal items.

Di Lullo's invention might initially seem as absurd as many of the others on this list, but it's one that had practical benefits. These goggles for dogs, inspired when she and her husband noticed their pooch seemed to be sensitive to sunlight, quickly took off. Di Lullo quit her job as a software engineer and, along with husband Ken, focused on the company. In 2012 it reported revenues of $3 million.

Where is she now? Roni Di Lullo is still running Doggles with her husband, Ken, extending the company's product line beyond the original eye protection.

Anders was a high school teacher in Wisconsin when he came up with the idea for these popular novelties in 1983. He eventually paired with Eugene Murtha, president of Main Street Toy, to distribute them.

And by 1990, demand was so intense that the company stopped counting how many they sold and measured instead by weight. The New York Times, at the time, said 1990 revenues were expected to land between $6 million and $8 million, compared to $2.5 million in 1989.

Where are they now? Anders left the classroom and is now owner and lead designer of Allied Industries.

The Snuggie might be better known in the U.S., but Clegg's Slanket was the forerunner of the mass-market wearable blanket. Clegg, bothered that he couldn't keep warm as he watched late-night TV, invented the Slanket in 1997, when he was a freshman at the University of Maine.

With a little help from his mom, who sewed the original prototype for him, he launched an empire that made $7 million in 2009. Allstar Products later came out with a less expensive version of the product and made even more. (Sleeved blankets, it turns out, aren't patentable.)

Where is he now? Clegg continues to run his Slanket empire.

Telfer's oldest son had a favorite stuffed animal he took with him everywhere, sleeping on it so much it began to flatten out. That's when inspiration struck. Telfer and her husband, owners of CJ Products, made the stuffed animal that flattens out to a pillow and earned $300,000 their first year. The next year, revenues hit $3 million, then $7 million the year after that. And in 2010 they leapfrogged to $300 million.

Where is she now? Telfer remains owner of CJ Products and has expanded the Pillow Pet line through a series of licensing agreements to companies like Disney and Nickelodeon.

Carter's mother was a clairvoyant in Cincinnati, giving him the inspiration for a fortune-telling gadget. He eventually paired with Bookman to design the device, but the original was nothing like the novelty we know today. Instead, the original Magic 8 Ball was called the Syco-Seer and was encased in a crystal ball.

Carter died before the patent was granted in 1948. The Syco-Seer flopped, but Chicago's Brunswick Billiards liked the product and commissioned Bookman to repackage it in a black-and-white 8 ball. Bookman's company was later bought, and the Magic 8 Ball changed hands several times. Today it's owned by Mattel.

Where are they now? Carter, as mentioned, passed away in the 1940s. Bookman died in 1993.

Adams, a licensed psychologist, has said he invented the skate/shoe fusion as part of a midlife crisis. As he dealt with a divorce and difficult career, he daydreamed about being able to shift his weight and just roll away. In December 2000, that dream became reality—and an instant hit—selling more than 1 million units its first year.

Where is he now? In 2010 Adams exited the company, quietly selling his 4.7 million shares for more than $10.6 million. (He had previously sold shares in 2006—after the company went public—for $41.2 million.)

A makeshift creation put together on a whim by this fax machine salesperson has since turned into an empire that made $14 million in sales its first two years.

Blakely came up with the idea for her body shaper when getting ready for a party. To look slimmer in her outfit, she cut the feet off a pair of pantyhose. Realizing that her idea worked, she spent the next couple of years refining the concept and looking for a hosiery manufacturer to back the idea. She took charge of everything from sales to marketing to logistics initially, building her company from the ground up.

Today, Forbes estimates her net worth to be more than $1 billion.

Where is she now? Blakely continues to oversee the growing Spanx business.

The Spain brothers weren't the inventors of the iconic yellow smiley face you see on stickers, keychains and takeout bags. That would be Charlie Bell, who drew the figure for an insurance company in 1963 and was paid just $45. Neither Bell nor the insurance company copyrighted the images, though. And when the Spains saw how popular it was, they added the phrase "Have a Happy Day" and quickly secured one.

Throughout the late '60s and early '70s, buttons adorned with the face and phrase sold more than 50 million units.

Where are they now? n the 1980s the Spains opened the Dollar Express store, which continued to sell the smiley face. In 2000, Dollar Tree bought their chain for $500 million. They have stayed out of the spotlight since.