1 can (13 oz.) evaporated milk
1/2 c. lemon juice
1 c. sugar

Put milk in freezer in bowl until icy crystals form on top. Then whip milk until stiff. Add sugar and lemon slowly. Pour into graham cracker crust and freeze.

CRUST:

1 1/2 c. graham cracker crumbs
1/2 c. melted butter
3 tbsp. sugar

Or buy crust already prepared.