Ribbon Jello

6 or 7 pkgs. Jell-O in different colors
1 Pint Sour Cream
1/2 Pint Cool Whip

Add 1 c. boiling water to 1 pkg of Jello.  Put half in pan.  Add 1 T. Sour Cream to the remaining jello in bowl.  Use an electric beater.  When first layer is set enough to hold the next layer, add the jello and sour cream mixture.  Wait until set enough to hold another layer.  When that is set, start over with next pkg. or Jello.  Keep layering until all layers are used up.  Top with whipped topping and leftover sour cream.  Sprinkle with chopped nuts, if desired.  .