Imagine my surprise when I searched Icee on Wikipedia and learned that Slurpees were made by the very same company, the ICEE company. This guy Omar Knedlik invented the Icee machine in the 1960s and in 1967 7-11 bought the rights to use the machine and trademarked their version of the drink now called Slurpee.
For years I've sat by and listened to countless arguments of Icee vs. Slurpee in the never ending debate of simplicity vs novelty. Blue and Red vs. Mountain Dew's Blue Shock and Code Red. There's so many Slurpee flavors it's hard to keep track, but I'm pretty sure how the recipes differ from one to the next:
Pina Colada flavor: 99% sugar, 1% white dye.
Minute Maid flavor: 99% sugar, 1% orange dye.
Starburst Dragon Fruit flavor: 98% sugar, 1% red dye, 1% mythical dragon.
Slurpee's efforts continue to this day as they add coconut and other weird flavors that you're forced to try. Some flavors you regret, and some you wish had never gone away (Bring back Mutant Berry. Who's with me?).
Remember that time you put a Coke in the freezer, forgot about it, and saw it's remains all over your Kid Cuisine frozen dinner boxes? I do. You were such a stupid kid.
That's what makes Slurpee's Coca-cola flavor so important in our lives and a staple in everyone's biweekly beverage habit.