One who regularly visits Wisconsin Dells to the point of being passionate about same, reinforced by a souvenir T-shirt worn regularly as a walking billboard of sorts, or interjects or otherwise alludes to Wisconsin Dells in conversation back home. Patterned on "Deadhead" (i.e., Grateful Dead fans) and "Parrothead" (i.e., Jimmy Buffett fans).
I couldn't help but notice so many Wisconsin Dells T-shirts at the Jewel when I was shopping the other day; seems those Dellsheads have been a little more obvious in their presence since the season ended.