In the fictional context of Planet Venison, Mike Dubek is Venison Skidmore's mortal enemy, basically a disgruntled former bandmate that lives across the Teton range in Afton, Wyoming while he plots the destruction of Venison and his colony.
In the world of reality, Dubek is the collective spawn of a few minds that used to work together at the Salt Lake office of the Natural Resources Conservation Service in the late 90's. Josh worked there as a cartographer, and one day learned that two of his co-workers, Ron Nichols and Mike Domier, had a habit of signing this mysterious name on office birthday cards. Whenever a card would come through, one of them would sign "Mike Dubek", with the idea that the office was so big that most employees would have no idea that Dubek didn't actually work there. Josh loved the idea, and decided that it needed to be brought to a larger audience. So for the last seven years, Josh has signed "Mike Dubek" on just about every wedding reception guest list he's come across. If he goes on a date, he signs "Mike and Delores Dubek" for good measure (Delores is--in the fictional world, remember--the 14th Mrs. Dubek. The previous 13 are deeply involved in a campaign to assassinate their former husband.).