1/2  cup  Sugar
1  cup  Water
6  ounces  Frozen orange juice concentrate
6  ounces  Grapefruit juice concentrate
28  ounces  Ginger ale
1/3  cup  Grenadine syrup

Mix sugar and water in saucepan; boil for 5 minutes. Cool. Add frozen concentrates; refrigerate. Chill for several hours. At serving time, add ginger ale and grenadine syrup.