Here is a recipe that was on Cool Whip a few years ago & I make this often.
1/2 - cup lemon juice, I use 3/4 cup because I like a tart pie
1 - can Eagle Brand Sweetened Condensed Milk
1 - 8 oz. Cool Whip
Graham Cracker Crust
Mix lemon juice, condensed milk together, them fold in cool whip. Pour into graham cracker crust & chill for 2-3 hours. It really is easy & delicious.