You can use any shape. It doesn't have to be a bunny. Just trace a shape or cookie cutter. This would be cute for any holiday, just use an appropriate cookie cutter to trace and cut out the shape, then whatever yarn works best for that holiday!
Teal Rosette Ombre Cake - Different-sized rosettes in shades of teal create an amazing ombre effect on this cake. The Wilton Method of Cake Decorating, Course teaches how to pipe these rosettes and other amazing decorating techniques.