Quite possibly one of the best Slurpee flavors of all time, the Sour Watermelon Slurpee never even made it to some 7-Eleven locations. It was probably being test-marketed, and seemed to be doing quite well, given that they were always having to churn up a fresh batch. This particular icy concoction was pink, tasted approximately like watermelon candies, and had a lot of citric acid in it, which made it similar to a semi-liquid Sour Patch Kid. Unfortunately, some people found out the hard way that this beverage was not meant to be consumed without a straw, and it burned the hell out of their lips; others found that it was just too acidic anyway and suffered horrible gastric consequences after drinking it. The flavor was pulled from the machine in the only 7-Eleven I'd found it in less than a month after its introduction, and it is believed that this had something to do with complaints about the acidity of the substance.