You need these ingredients (cold):
1. Grapefruit Juice (or you can squeeze fresh Grapefruits)
2. Cola (Coke or Pepsi)
3. Spring Water (you can take tap water if yours is good).
Step1: 
Pour
1 part grapefruit juice.
Step2:
Add about 1 part Cola.
Step 3: Add 8 parts Spring Water. Add some ice.
Follow the proportions in the picture. You may want to experiment a little
with varying the quantities and come up with your own recipe.
