A Bird told me while sitting in a tree by itself:
Well, not exactly the same way as originally they used real coca leafs , something they still do btw though the have de-cocainized the leafs before adding them now. Someone probably have some great parties somewhere with all that cocaine they extract out of those leafs before making the Coca Cola

I've heard from Coca Cola Company that the import around 200 tons Coca leafs yearly to make the Coca Cola soft drink in USA.
Anyway, what I do is simply spice up my Coca Cola with some fresh cocaine and then flush it down

Gently numbs the mouth and throat and the effects come on more slowly and last longer.
Of course you need to use more of it when taking it orally, so this probably would be best for those whom have a nice supply and can afford using some extra.
If you are like me and live in a country where Coca leaves are legal you could of course get some fresh ones and add them the traditional way yourself. Not sure how much would be needed, but I suppose you could grind up some in a blender with some water, then boil it some to get out the goodies, filter off the leafs and discard them, and evaporate down the coca tea until its just a little bit left that is concentrated, and add that to your Coca Cola
Then the Bird flew away and I heard no more that day