Doc Holiday is a soda that you will see no where else in the world, but is widely available in the little town of Benson. Strangely enough, I have never seen it in Tucson, even though it is supposedly produced here.
Go to either the Horse Shoe Cafe or the local Dairy Queen and ask for it. It's available in the same fountain as other, more well-known sodas.
The taste is somewhat similar to Dr. Pepper.
Learn basic Spanish pronunciation. Most people around here (myself included) find it amusing when tourists say things like 'aw-ka-tilo' instead of 'oh-ka-tee-yo'... and they are 'HA-le-pen-yos', not 'ja-le-pen-os'.