McDonald's served the Grimace birthday shake as a part of the Grimace birthday meal that included a choice of Big Mac or 10-piece Chicken McNuggets, a medium French fry, and the tasty purple milkshake. If you didn't have the chance to try the milkshake yet, I have sad news to report. The McDonald's official Twitter had this to say about the milkshake, "U made me feel so specialll ty say goodbye grimace nowww." While we're disappointed to see it go, continue the celebration by preparing the tasty dessert in the comfort of your kitchen.