One of the nicest ways to drink coconut juice is roasted over a fire or barbecue. For this you will need the young green coconut (not the brown husk older coconut). Cut off the outer husk as much as you can, then place it in the coals and keep turning it until its blackened and roasted all over.
It's very easy to open after it's roasted, you can simply push a knife into the eyes of the coconut and pour out the juice. Drink it while it's warm.