Prepare six disposable decorating bags with tip 5; fill separately with green, yellow, pink, burgundy, violet and teal icing. Prepare additional decorating bag with tip 7 and navy icing. Prepare final decorating bag with tip 5 and white icing.
Using tip 5 bags, pipe dots around cake. Using tip 5 bag with white icing and heavy pressure, pipe “YAY!” on front of cake. Outline message using tip 7 and navy icing.