The precursor to the Slurpee was invented in the late 1950s by Omar Knedlik of Kansas City. Knedlik owned a Dairy Queen, and when his soda fountain broke, he kept soda in the freezer to keep it cold. The soda would become slushy, and his customers loved it. He eventually developed a machine to create the 'frozen carbonated beverage' and called it the ICEE. In 1965, 7-Eleven licensed the technology and renamed the drink the 'Slurpee' to describe the sound made when drinking it through a straw. A key scientific feature of the Slurpee is that it uses a pressurized system to keep the slush from turning into a solid block of ice, ensuring that every sip is a consistent mixture of syrup and tiny ice crystals.