The Wilton number 233 multi opening decorating tip is great for character cakes and cupcakes, because it pipes multiple pull-out lines used for hair and fur. It is also extremely useful for piping flower centres and piping grass.
Fit the decorating bag with Multi-Opening Decorating Tip 233 and fill 1/2 full with medium consistency icing. Hold the decorating bag 90° straight up; the tip should be 3mm above surface. Squeeze bag to form grass. Pull up and away when icing strand is long enough, stop pressure and pull tip away. Grass will be neatly formed only if you stop squeezing before you pull tip away. For a more natural look sometimes pull tip slightly to the right or left, instead of straight up. Remember to keep clusters close together so cake does not show through.