(Optional) Set aside two pineapple cubes to use as a garnish, slicing them halfway through and placing on the glass rim.
Pour the coconut water and rum into a blender. Add pineapple cubes and cover. Blend until mixture is smooth and no chunks remain. If mixture is too thick or difficult to blend, add another ¼ cup of coconut water.
Taste and add more rum as desired.
Pour into glasses and enjoy.
*3 ounces = 6 tablespoons = 2 filled shot glasses
Clear rum can be substituted with dark, spiced, coconut, or another fruit flavored rum.
Coconut water can be substituted with coconut milk, pineapple juice, or orange juice.
Low calorie version: substitute half of the frozen pineapple with ice.
Non-alcoholic version: substitute the rum with more coconut water.
If you are using out of season/frozen pineapple that's not as sweet as usual, you may want to use pineapple juice instead of coconut water to give some additional sweetness and pineapple flavor to your drinks.