1. Pour the corn syrup in a shallow bowl. Dip a toothpick into the food coloring, and stir a very small amount into the syrup to combine. Hold a glass by the stem, dip rim into the syrup mixture, and turn glass slowly, coating entire rim. Turn the glass upright, allowing mixture to drip down sides. Dip the remaining glasses. Set aside.

2. Whisk together drink ingredients. Place 2 1/2 cups ice in a blender, and add 1 cup drink mixture. Blend until smooth; add more pineapple juice if mixture is too thick. Repeat with remaining ice and mixture. Carefully pour into prepared glasses; serve.