1. Heat oven to 375 degrees F. Line 18 muffin cups with baking liners. In a large bowl, combine flour, sugar, baking powder, baking soda, and salt. Stir in orange juice, oil, bananas, orange peel, and nuts (if using), just to combine.
2. Pour batter into baking liners, and bake 18 to 22 minutes, or until toothpick inserted in center of a cupcake comes out clean.
3. In a large bowl, with electric mixer on medium-high, beat margarine until light and fluffy, about 2 minutes. Gradually add confectioners' sugar, and beat to combine. Add the water and vanilla extract, and beat until fluffy. Tint frosting dark orange, and frost cooled cupcakes. Use chocolate chips for eyes, and pipe a smile onto each cupcake face with decorating gel.