(TrendHunter.com) The 7-Eleven Birthday Cake Slurpee is one of the latest frozen refreshment flavors from the convenience store retailer that will call to mind celebratory desserts for an unexpected taste experience.... (TrendHunter.com) The 7-Eleven Birthday Cake Slurpee is one of the latest frozen refreshment flavors from the convenience store retailer that will call to mind celebratory desserts for an unexpected taste experience....