NEVER add rubbing alcohol!
I will repeat this....NEVER.
Rubbing alcohol is isopropyl alcohol which is a very potent poision to the body...it will KILL you if consumed. KILL, not like, make you sick, but you will die if you consume even fairly minimal amounts of isopropyl alcohol, and most rubbing alcohol is about 70% (140ish "proof").
Ethanol is what we commonly refer to as drinking alcohol, and is a mild poison which is what gives you the drunk effect. This is completely different from isopropyl and the two should never be confused.
This whole death thing is why mouth washes use ethanol rather than isopropyl, which is actually better at killing bacteria...only one problem, if it's ingested it can kill the "swisher" too (i.e. you).
The reason that mixing water with clear alcohol is "good" or doesn't really do much is because clear alcohol is exactly that, ethanol (produced by different methods...i.e. by way of potatoes for vodka) diluted with our good friend water...there's no magic to it...so in essence you're stricktly diluting it, and if the water is pure you're adding nothing to it that wasn't there, just a less harsh taste and the requirement of consuming more to get drunk.