Trim the ends of the rhubarb, peel the stalks, and cut them into pieces.
In a pot, bring the coconut milk to a boil, reduce the heat, and cook the rhubarb pieces on low heat for a couple of minutes until they are soft (with the lid on).
Leave to cool completely.
Blend with the pineapple juice and the peeled bananas until creamy and smooth.
If you like the cocktail sweeter, add sweetener of your choice.