a day or two in advance,
In ice cube trays, Freeze 2 or 3 trays each with:
Orange Peach Mango Juice or plain O.J.
Store them in ziploc freezer gallon size bag.
Dump a few handfuls of the colorful ice cubes into a glass pitcher, then pour in a bottle of Fresca (preferred) or Sprite. The carbonation does something to the ice cubes to make them start breaking down. You can either serve the drink like this, OR to make it slushy, let the ice cubes soften in the fridge for an hour or two before serving. Once the Fresca is poured over it, just mash it up a bit with a spoon. YUM. Another crowd pleaser!