Divide your cake batter into thirds and then color one third blue, another third yellow and the last third red. Spoon about a tablespoon of each color into the cups and bake as normal.
Ladybug says that they taste great but next year I think I'll just fill the cupcake liners with frosting - almost none of the kids in her class at the cake!
Now for the easiest and tastiest buttercream frosting:
2 cups butter or shortening or 1 cup of each*
1 tsp salt
2 tsp flavoring of your choice
1 cup water
3-4 pounds of powdered sugar
Cream butter/shortening, salt and flavoring until very smooth. Add sugar and water alternately. Once everything is incorporated beat on medium speed for 8 minutes. Frosting will be very soft at this point. Let chill for 10 minutes before using.
*Note - frosting will hold up better outside of the refrigerator if there is more shortening than butter but will taste better with more butter. Please balance your priorities accordingly.