Spatula ice tops of cupcakes with white buttercream icing. Tint remaining buttercream icing red, blue, yellow or other favorite colors. Pipe tip 8 or 12 ball balloons. Holding tip slightly above surface, squeeze the bag, applying a steady even pressure. As the icing begins to build up, raise the tip with it, but keep the tip buried in the icing. Stop squeezing, bring the tip to the surface and use edge of tip to shave off any icing point.