Place frosting in piping bag. For each bunny, cut 2 mini marshmallows in half and use frosting to attach them to a large marshmallow to form arms and legs. For the face, attach 2 mini marshmallow halves for cheeks. Use white jimmies, black nonpareils and heart-shaped sprinkles to form whiskers, eyes and nose. For the ears, cut a large marshmallow in half diagonally. Dip each sticky side in colored sugar and use frosting to attach the ears to the top of the large marshmallow. Use frosting to connect the 2 large marshmallows; let stand until dry.