Many businesses succeed because they’re a simple but brilliant idea. Other businesses succeed because they fill a niche that no one else thought of filling. It takes a brilliant mind, a lot of courage, and some excellent business acumen to get a successful commercial enterprise going.

And then sometimes all you need to start off is an insane idea that no one thought could possibly work. There are a ton of great stories about businesses which filled gaps in a niche or created new markets. Frankly, those are not on this list.

While having the guts and business know-how still apply, this here is a list of crazy business ideas that you’ll still scratch your head wondering how these founders even came up with the idea. Then continue scratching as you realize they actually create a viable business model from them. Not only have some of these succeeded but many are still raking in millions of dollars a year.

15. Antenna Balls

Ever thought about grabbing a ping pong ball and putting it on top of an antenna? Then maybe paint a happy face on it? No? Then I bet you wouldn’t think you could become a multi-millionaire by doing that and selling them online, then. But that’s exactly what Jason Wall did. His company In-Concept Inc. made over a million dollars in its first year alone. He continued selling millions of these little painted plastic balls via the website Antennaballs.com. Wall’s company has since merged with another antenna ball manufacturer, HappyBalls.com, and continues to sell these plastic toppers.

14. Santa Mail

Christmas is a kid’s favorite time of year. Every year, they believe a magical fat man in a red suit climbs down their chimney to deliver them presents. Enterprising entrepreneur Byron Reese decided to go one step further and got a postal address in Alaska. From there he started his Santa Mail business where parents pay $10 for personalized letters from jolly old St. Nick to be sent to their child. Since 2001, Reese has sent over 500,000 letters and counting. He didn’t even need to put on the costume and work at the local mall to pretend to be Santa Claus, and has made a lots more money doing it his way.

13. Geese Police

Anyone who has ever come in contact with Canadian geese knows that they can be real jerks. When they take up residence they become more of a problem, leaving — um — traces of their presence behind. Getting rid of them became a huge problem for David Marcks who was working as a groundskeeper at a golf course where 600 geese decided to set up shop. Through some trial and error, he discovered that Border Collies possessed distinct traits to not only chase away geese but keep them from ever coming back. Thus, Geese Police was born. Call them to…Get the FLOCK OUT!

12. Designer Diaper Bags

Tired of carrying around diapers in freezer bags to keep them from getting scrunched up inside her purse, 34-year-old mother of three Christie Rein decided enough was enough. She resolved to design a custom diaper bag that was sleek, compact, and stylish. Along with her husband, she created a diaper bag big enough to hold two to four diapers along with travel wipes but small enough to fit inside of a purse. These designer diaper bags are now available in more than 1,000 stores across the United States, online, and in countries such as Japan, Canada, UK, Spain, Dubai, Germany, Sweden, and Australia.

11. Ashley Madison

Dating sites are nothing new. But when one of them carries the tagline “life is short, have an affair” you know they’re trying something a little different. This isn’t a site that avoids controversy, it is one that courts it. So not only do they attract negative publicity but something along the lines of 1,800,000 users per month. Using the site does come with some risk. In 2015 Ashley Madison’s servers were hacked and user information was posted online. Even so, there’s no denying founder Noel Biderman (who is, ironically, happily married, by the way) struck gold with the idea.

10. Crocs

These shoes are ugly as hell. Crocs were designed by three friends from Boulder, Colorado during a sailing trip. The trio were intrigued by the idea of a spa shoe that was made for comfort and daily use. They acquired a Quebec-based company called Foam Creations. That company developed a foam clog, originally developed as a boating shoe, which was made from a patented foam resin called Croslite. Even though these shoes tend to be the butt of many jokes, the company pulls in hundreds of millions of dollars in revenue per year. You definitely know someone who walks around the house in a pair of crocs – if you don’t yourself.

9. Pet Rocks

The original crazy business idea that actually worked has to be the Pet Rock. In 1975, Gary Dahl, an advertising executive from Los Gatos, California, was out at a bar one night listening to friends complain about their pets. He joked that he would prefer to keep a rock as a pet around. Then he decided to write a 32-page official training manual and began selling them. They were packaged in boxes with air holes and little straw beds to lay on. The fad lasted only six months but by then Dahl was $15 million richer. The lesson hereis that sometimes it pays to take jokes seriously. As of 2012, pet rocks have been made available yet again.

8. Plastic Wishbones

Have you ever finished eating a turkey dinner with your family and wondered why there’s only one wishbone? How come only two people could attempt to make a wish? Yeah, I’ve never wondered about that either, but one man named Ken Ahroni did. So he went out and started Lucky Break which mass produces plastic wishbones. They produce over 30,000 wishbones per day including personalized and custom designed versions. Their sales top $2.5 million per year. Who knew so many people want the chance to make a wish so badly that they would resort to plastic versions of the real thing?

7. Zynga

I missed out on the FarmVille craze. I still don’t get it but a lot of my friends loved playing that game way back when it was all the rage. Some still do. What really confused me was that you could buy virtual currency with real money in order to purchase virtual goods that could only be used in-game. Users were encouraged to spend money to buy nothing. And they did. A lot of nothing. Zynga made $1 billion by 2011 in sales, partly due to the sale of virtual goods. Even though the company has waned, it set the standard of how to make a killing via in-game purchases.

6. Million Dollar Homepage

If selling virtual currency for virtual goods doesn’t make sense to you, how about selling pixels on a website? Alex Tew of Wiltshire, England decided to do just that in order to get himself through university. He constructed a website with a 1,000 by 1,000-pixel grid and sold each pixel for $1 each. Multiple pixels could be bought and turned into a link making the website a giant interactive billboard. The goal was to make $1 million which he reached within a few months. Tew went on to co-found the meditation app Calm but his million dollar website still stands today as a piece of bizarre internet history.

5. Dog Goggles

Back on the practical side of crazy business ideas, we get goggles for dogs. Or Doggles as its inventor, Jill Doyle, calls them. I know, I know, seeing a dog wearing sunglasses looks and sounds hilarious, but there is a practical reason for it. It protects your dog’s eyes from the UV rays from the sun. There are even prescription lenses for dogs with impaired eyesight available. Doggles now brings in about $5 million per year. Not bad for something that makes your pooch look like he’s ready to pilot a plane.

4. Square Watermelons

In another weird business idea that has some semblance of practicality, this one comes from the land of the rising sun. Square watermelons were invented in Japan in the 80s as a way to save space in compact refrigerators. The shape also makes them far more convenient to transport. However, the cost and labor of making them are really high so these cubic fruits tend to be expensive. Like, anywhere between $75 and $100 per melon. Because of that, they tend to be sold as novelty items but they’re still popular in Japan as new shapes, such as hearts and pyramids, are being sold.

3. Irish Dirt

For the Irish reading this, you probably know what Auld Sod is. For the rest of you, here’s a quick primer: it’s Irish dirt. A lot of Irish history can be traced back to its soil. Noticing that his Irish-American compatriots seemed to miss soil from their home country with profound nostalgia, businessman Alan Jenkins decided to start a company. The idea is simple, he would import dirt from Ireland and sell it. In order to get around the import restrictions on importing soil from another country, Jenkins teamed up with an Irish-American agricultural scientist named Pat Burke to patent a sterilization process. The Auld Sod Export company was born and raked in millions of dollars when it was launched.

2. Bottled Water

Make no mistake, bottled water is one of the craziest business ideas that has ever worked. While most people think that bottled water is better for them and from fresher sources, the reality is actually quite the opposite. Tap water is far more regulated. However, bottled water from companies like Aquafina or Dasani are regulated as stringently as tap water — because they come from municipal water sources. In the end, you’re paying a premium for bottled tap water. This idea is almost as crazy as bottling air in a can and selling it. And yet bottled water is set to outsell soda this year.

1. Bottled Air

Bottled water is almost as crazy as bottling air in a can and selling it. So of course bottled air is on this list. A Canadian startup company called Vitality Air started selling fresh air captured from the Rocky Mountains in Ziploc bags for $1 on eBay. Now the company sells cans of air for $32 each. The company was started to sell air as a novelty but soon orders started to skyrocket. Their major buyers turned out to be smog riddled areas in China like Beijing. For those of you who want a little something extra, Vitality Air also sells oxygen in flavors like strawberry, grape, and root beer.