GREASE and flour 13x9-inch baking pan; set aside. Prepare cake batter and bake in prepared pan as directed on package. Cool 15 min.; remove from pan to wire rack. Cool completely.
TRIM corners and sides from cake to resemble football shape. Reserve trimmings for snacking or another use.
FROST cake with frosting. Use decorating gel to add the "laces" to the "football." Store in refrigerator.