With more than 14 million cups consumed every month, 7-Eleven’s Slurpee might be the most popular frozen beverage in the world. In honor of the iconic slushie, which has been around for more than half a century, we’re dispensing some facts on its history, Slurpee milestones, and why you can’t fill a kiddie pool with the slush.

1. The Slurpee's invention was accidental.

Chris Weeks/Getty Images for 7-Eleven

Slurpee’s origins have roots in that oasis of deliciousness, Dairy Queen. In 1959, franchisee Omar Knedlik found that his soda fountain wasn’t working. After freezing some pop bottles to keep drinks cool, he discovered customers loved the icy consistency. Using an automotive air conditioner, Knedlik invented a machine to dispense pure Tundra-sourced slush, called it ICEE, and then licensed the equipment to 7-Eleven in 1965. The company renamed it Slurpee in 1966 in honor of the sound a person makes while trying to slurp up the gunk through a straw. (The ICEE brand is still used in other convenience chains.)

2. A TV commercial helped Slurpee sales soar.

Slurpee sales were idling at an average of 50 per store per day until 7-Eleven launched its “Strange Things” series of television commercials. In one spot, a man swears his life was modest until he sampled a Slurpee—the next day, he became an airline pilot. Even though the ad didn’t explain what a Slurpee was, it created so much interest around the product that individual store sales soared to 300 a day.

3. The Slurpee revolutionized the straw.

As Slurpee began to conquer the convenience cold-drink market, 7-Eleven realized that customers were having issues getting the remaining bits of syrupy chunks from the bottom of the cup. The solution? Inventor Arthur Aykanian’s spoon straw, which added a little scoop at the end. Debuting in 1968, it has become synonymous with Slurpee. In 2003, the company took Slurpee delivery development further with an edible straw. The candy rod was bendable until it hit the ice-cold liquid, where it stiffened into a useable utensil.

4. There was a Slurpee single.

The 1970s were a strange and terrifying time for pop culture: the decade gave license for 7-Eleven to release a single on 45 RPM vinyl, “Dance the Slurp,” as a promotional track for the drink; it was given out free in stores. The piece features a groovy tune accompanied by a slurping sound. It’s well worth your time.

5. “Brain Freeze” is trademarked by 7-Eleven.

Everyone is aware of the dangers of drinking a Slurpee too fast: searing, thudding pain in the cranium that can bring a sturdy individual to his or her knees. While brain freeze started out as a colloquial term, 7-Eleven saw the marketing opportunities—and trademarked the phrase. The actual medical term for that type of rapid-onset headache caused by an overabundance of cold temperatures to a key artery in the throat is sphenopalatine ganglioneuralgia. You can make it dissipate faster by pushing your tongue against the roof of your mouth or drinking something warm.

6. You could chew Slurpee chewing gum.

For decades, 7-Eleven was pretty protective of the vaunted Slurpee brand, preferring to keep it to ice-encrusted drinks and non-edible items like keychains. In 1998, the company had a change of heart and expanded the Slurpee umbrella to include a frozen ice pop and blocks of bubblegum that had a liquid center.

7. Some Slurpee cups were made from waveforms of mating whales.

For a promotional stunt in Australia in 2015, 7-Eleven recorded a series of radio spots featuring whales mating and screaming soccer fans. The waveforms—visual representations of the noises—were then used to create a 3D-printed series of special cups that customers could get in stores or print at home (if they had a 3D printer).

8. Manitoba, Canada is the Slurpee capital of the world.

Though 7-Eleven doesn't give specific numbers, the Canadian province of Manitoba—and Winnipeg in particular—has spent more than two decades as the world's most enthusiastic community of Slurpee sippers. "Slurpee has been the centerpiece of so many Canadian memories and we’re very proud to continue to grow with our country for years to come,” Doug Rosencrans, a longtime 7-Eleven executive, said in 2019.

9. Adults used to be ashamed to drink Slurpees.

Chris Weeks/Getty Images for 7-Eleven

For all of Slurpee’s success throughout the 1970s and 1980s, there was one problem: adults were slightly embarrassed to be seen with one. Because much of the marketing was targeted at children, adults would sometimes ask for Big Gulp cups to deposit their slush in. Taking note of the ignored demographic, 7-Eleven partnered with MTV in 1995 to sponsor its summer "Beach House" programming block: young adults could use a slide that ran right into a pool of Slurpee. Sales of the drink rose 10 percent that year.

10. There was once a dual-chambered Slurpee.

In 2011, to celebrate Slurpee's 45th birthday, 7-Eleven decided to pioneering a new method of drink delivery by introducing a highly innovative dual-flavor Slurpee. Customers could choose two flavors that would be dispensed into one cup with two chambers; a dual-piped straw could be inserted, allowing them to either enjoy a mixed drink or activate a valve that would allow for one flavor to be sucked up at a time.

11. 7-Eleven's Bring Your Own Cup Day got a little out of control.

During promotional stunts in 2015 and early 2016, 7-Eleven allowed patrons to bring their own container to Slurpee machines for a flat price of $1.50. While most patrons kept their cups to reasonable portions, a few carried in kettles, fish bowls, teapots, and even a plastic sled. One consumer brought an inflatable swimming pool. 7-Eleven eventually mandated that containers had to fit through a cardboard measuring hole to ward off anyone thinking of bringing in a trough. Eventually, the company began noting in press releases to: "Please leave trash cans, kitchen sinks, and inflatable swimming pools at home, as they are not eligible."

This story has been updated for 2021.