I found this off another site, Here go's
Quick and Easy Watermelon Pie
1 can sweetened condensed milk
4 oz container refrigerated non-dairy topping, thawed (cool whip)
1/4 cup lime juice
2 cups watermelon balls
1/2c. heavy cream
1 9inch. grahm cracker crust
Fold together milk and topping. Add lime juice. Fold in watermelon balls,
(saving 5 w-balls for garnish) Pour into graham cracker crust. Place the
5 balls on top for garnish. Chill for 2 or more hours before serving.
Enjoy!