Happy birthday to that life of the party drink, the Frozen Margarita and the original frozen margarita machine! It all started in Dallas. That’s where restaurateur Mariano Martinez says customers at his original location on Greenville Avenue were grumbling about margaritas that weren't cold enough. He says he got the idea for the frozen margarita machine while watching some kids buy a Slurpee in a 7-Eleven. Mariano bought a soft-serve ice cream machine, monkeyed with it, and made the first frozen margarita on May 11th, 1971. That original machine is on loan to the Smithsonian in D.C.