The night before, layer the lime slices in a bundt pan, cover with 3 cups water, and freeze solid: this ice ring keeps the punch cold for hours without watering it down.

Sugar the rims of the serving cups in advance: dip each rim in a little pineapple juice, then in red sanding sugar, and let them dry upright.

In the largest punch bowl available (at least 1.5 gallon capacity), pour in the green fruit punch.

Add the pineapple juice and stir gently to combine; the mixture should look an even, slightly cloudy green.

Just before guests arrive, pour in the ginger ale around the edge of the bowl so the fizz holds.

Unmold the ice ring, float it on the surface, and ladle the punch into the sugared cups, finishing each with a candy heart.