First... son??
Second, you actually think that Coke is a watered down version of Pepsi? Seriously?
The term "nah son" is used before saying something contrary. It doesn't always have to be gender specific.
I mentioned in another post that Coke seems to go flat too fast so it's not exactly my favorite. I'll drink it, but not if I have other choices. Vanilla Coke would be the Coke I'd drink if I want a Coke.