In ShortStrawberry-pink and milk-white are the signature colors of the fast-food realm's ice-cream leader. Customers belly up to counters in food courts or free-standing shops where rows of ice cream-packed tubs stand ready under stacks of sugar cones and cardboard cups. Originally, the "31" promised a different flavor every day of the month. Nowadays, the number signifies constant variety--from Cherries Jubilee and Rocky Road to shakes, smoothies and custom-made cakes.