Because to me, it tastes exactly like Mountain Dew and Mountain Dew Code Red mixed together! Could you come up with a more awesome combination if you tried?
(Also it's even better if you mix it with rum or vodka or some other form of alcohol.)
Mixes well with Russian Standard vodka and gives a good buzz. I'm sipping on it right now.
I'll also try it mixed with whiskey in a minute. I've got a fifth of Canadian Club my brother bought me back in October, might as well finally open it and put it to good use!
I also have some Jameson, but I would never waste good Irish whiskey by mixing it with Mountain Dew. With Canadian Club, it's cheapo blended stuff that costs fifteen bucks at most and if anything, the Mountain Dew Holiday Brew would make it more palatable.