Guests will stare wide-eyed as they watch clear water or soda transform into a vibrant color! must be magic! What you'll need: Plastic party cups, food coloring, ice, and any clear drink (like Sprite, Fresca and Ginger Ale). Place 2 to 3 drops of food coloring at the bottom of each party cup and let dry. Just before serving the drinks, fill each cup with ice to hide the food coloring. While each child watches, pour the drink over the ice.