For the crust: Mix the graham cracker crumbs, brown sugar, and melted butter together. Press it into the sides and bottom of a 9-inch (23 cm) pie pan. Place the crust in the refrigerator to firm up while you make the filling.
For the filling: In a large bowl, stir together the sweetened condensed milk and the Tang until combined and a shocking shade of orange. Add the sour cream and stir until smooth. Gently fold in the Cool Whip a little at a time until just combined so that you maintain the fluffiness.
To assemble: Pour the filling mixture into your graham cracker crust and smooth the top. Refrigerate for at least 4 hours.
Slice the chilled pie and serve it forth.
