This is the easiest key lime pie recipe in existence. And my favorite!
6 limes (or 3/4 cup bottled juice)
1 can sweetened condensed milk
1/2 8 oz container Cool Whip (More or less to taste)
1 or 2 drops green food color (optional)
Squeeze juice from limes into bowl with sweetened condensed milk and stir until a thickening occurs. Fold in Cool Whip and color as desired. Pour into Graham Cracker Crust. Refrigerate until firm. (At least one hour)