Optional: For a deeper blue colored cocktail, microwave coconut milk for 30 seconds to 1 minute until hot but not boiling. Add butterfly pea flowers and steep for 10 minutes, then strain them from the coconut milk.
Optional: For even more fun blue color, you can steep more butterfly pea flowers hot water, strain, then freeze it into ice cubes to use while making/in the drink!
Add coconut rum to a resealable glass jar and add half of the butterfly pea flowers. Shake lightly and allow to rest for at least 30 minutes or until the rum reaches a deep blue color. Strain flowers from the rum and set aside.
Add blue rum, (optional blue) coconut milk, and several (optional blue) ice cubes to a large glass and stir for about 30 seconds. Strain into serving glass.
Just before serving, add lime and pineapple juice for a color changing effect. Stir before drinking.