I'm assuming the walking taco is a bag of Fritos opened up with taco meat and toppings (sour cream, cheese, lettuce, etc) on top of the Fritos, and eaten out of the bag with a spoon or fork. At least, that's what it is around here.
If it's the "you don't have kids, why are you going?" DH and I tend to go with "Why ruin Disney with kids?!"
If it's the "are you going to Disney World *again*?" I tend to just shrug and smile knowingly. ;)