In a mixing bowl, combine condensed milk, Cool Whip and cream cheese. Then add lemon juice and incorporate evenly. Please note: the lemon/lime juice MUST be added last. The reaction of the citrus juice will start to harden your mixture almost immediately.
On the low speed of your hand mixer, blend well for around 2 minutes or so, just make sure all ingredients are incorporated. Immediately pour mixture into a waiting graham crust.
Refrigerate for an hour to and hour and a half.
