Water saturated with sugar.
The item id for Canned Cola in unturned is 80. You can use this ID with the commands below to spawn the item, give it to a player or buy it on a modded economy server.
Useable: Consumeable
Size_X: 1
Size_Y: 1
Size_Z: 0.25
Water: 30
Energy: 25
Blueprints: 1
Blueprint_0_Type: Repair
Blueprint_0_Supply_0_ID: 392
Blueprint_0_Supply_0_Amount: 1
Blueprint_0_Build: 27