Pour some simple syrup in a small bowl and the shredded coconut in another small bowl. Dip the top ¼ or so of your champagne glasses in the simple syrup and then in the shredded coconut making sure the rim is well coated. Set aside to dry a little.
Fill each champagne glass with 1 ½ ounces of EACH pineapple and coconut juices. Fill the rest of the way with the champagne or Prosecco. Serve immediately.
Simple Syrup is a 1:1 sugar water ratio syrup. To make combine equal amounts in a sauce pan ( example 1 cup sugar one cup water) and then bring a simmer stirring until all the sugar is dissolved. Chill completely in an air tight container until ready to use.