Related Clues:

• It gets flat over time
• Caffeine source, perhaps
• Coke, for one
• Designated driver's choice
• Coke or Pepsi, e.g
• Icee flavor
• Soft-drink selection
• Slurpee flavor
• Drink option
• Ginger ale alternative
• Slip coach missing chips and drink
• Pop option
• Coca-__
• RC, say
• Part of a fast-food meal, maybe