Line a glass loaf dish or a metal loaf pan with plastic wrap, allowing the excess wrap to extend over the ends and edges.
Spread slightly softened vanilla ice cream evenly over the bottom, keeping the sides as free of excess ice cream as possible. Return the dish or pan to the freezer until the ice cream is hard.
Add a layer of orange sherbet, and then a layer of lemon sherbet in the same manner.
To serve, invert the dessert onto a serving plate. Remove the dish or pan and plastic wrap. If necessary, use a knife or a narrow metal spatula to smooth the sides and top before slicing. Garnish with candy corn.