Coke is a pesticide and many Indian farmers use Coke as a cheaper alternative to commercial pesticides.
Instead of paying high prices for chemical pesticides many Indian farmers spray their cotton and chili fields with Coca Cola instead.
The Caffeine in Coca Cola is a neurological agent that wards off insects.
Plants also naturally create Caffeine which is also a neurological agent that naturally wards off insects.
Caffeine can also be found in leaves and seeds.
Coke as well as club soda or carbonated water contain the macronutrients carbon, oxygen, hydrogen, phosphorous, potassium sulfur, and sodium that are essential for healthy plant growth.
The absorption of these nutrients encourages more rapid growth in the plant.
However you have to be careful when using sodas on your plants as too much flavored sodas could easily damage plant roots, breaking their immune systems down and leaving them prone to disease and death.