In the desperate need to prove Coca-Cola has some real use in the garden, some people suggest that you can leave a bowl of the beverage out overnight so it will attract slugs. According to this belief, they are attracted to the sugary smell of the drink, then the acid will kill them when the drink it. Or they simply fall in trying to reach the delicious nectar.
However, try it yourself and see: you’ll discover no slug ever gets poisoned nor falls into the bowl to drown. Apparently, slugs don’t like Coca-Cola, possibly because it’s so very acid (the pH of freshly opened Coca Cola is about 2.5: extremely acid).
Beer does a better job of trapping slugs (see Attracting Slugs With Beer: Myth or Reality?), but even beer is a very poor slug control method. In fact, it tends to increase the local slug population.
So, the best way to use Coca-Cola as a slug deterrent is to drink it to give yourself extra energy before you go out slug hunting.