In a measuring cup, mix milk and red food color together thoroughly. Add chocolate syrup and whisk. Add ice cream and milk chocolate mixture into a blender along with the cake mix. Pulse or use milkshake setting on your blender. Serve immediately.
*What to do with the leftover cake mix? Save it in a plastic zippered bag for those cake batter milkshake cravings or before measuring it out, divide it in half and follow instructions on the box (using half of the ingredients of course) and bake 12 cupcakes with it. I do that all the time when I don't really need 24 cupcakes.