Add 1 oz of grenadine to your cup or potion bottle.
In a separate measuring cup or glass, combine the pineapple juice, blue curacao, and coconut rum. Stir to combine.
Using a wooden or metal skewer (or a spoon if you have an opening wide enough to use), angle the instrument diagonally, so the tip is touching the side of your glass or bottle. Gently and slowly pour the blue mixture down the instrument so it gently flows and sits on top of the red layer.
Make sure not to stir or shake and serve cold.