The semi-frozen soft drink concept was born in the 1950s at a Kansas hamburger restaurant.
Owner Omar Knedlik didn't have a soda fountain so he served his patrons slightly-frozen bottled soda from his deep freezer. The drinks were very popular with customers.
Knedlik later worked with a Dallas manufacturer to create equipment that froze soft drinks and served them in a slush form, according to a 7-Eleven press release. They called it an "Icee machine" and distributed it to various businesses and drugstores.
A machine was spotted in another store by a 7-Eleven manager who thought they would do well with the company and eventually brought them to 7-Eleven, according to the release.
The drink was sold in stores beginning in 1965 with the name '"Icee," but in 1967, 7-Eleven's in-house advertising agency renamed the drink 'Slurpee' because of the noise it makes when you drink it.
"The first time I heard that sound through a straw, it just came out 'slurp'," said agency director Bob Stanford, who coined the term, according to a 7-Eleven statement.. "We added the two e's to make a noun. It was just a fun name and we decided to go with it."
In addition to the new brand, 7-Eleven renamed familiar flavors like lime and cola with wacky names like "Fulla-Bulla" and "Kiss Me You Fool," according to the company.
Since then, 7-Eleven has marketed the beverage in conjunction with aspects of popular culture, including movies, television shows, video games and professional athletes. In the 1970s there were baseball collector cups, for example, and later monster-themed cups and cups with rock n' roll stars.
There have been hundreds of flavors and numerous limited-time-only options introduced over the years, Margaret Chabris, director of communications for 7-Eleven, Inc., told USA TODAY Network.
These include the yellow pineapple flavor introduced along with the DVD release ofThe SpongeBob SquarePants Movie and 'Woo-Hoo! Blue Vanilla' in 2007 to go along with the The Simpsons Movie. In May, 7-Eleven debuted a flavor endorsed by NBA star LeBron James called a "Sprite 6 Mix."
Linking flavors to contemporary events is probably what's kept the beverage popular for so long, Allison Cohen, founder of ad consultant firm PeopleTalk, told USA TODAY Network.
"The fact that they've done that shows that they know who their consumer is," she said. "It's a really great way to keep their brand current."
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