Someone who is so closely involved with certain fandoms (whether it be a book series, a tv show, a celebrity, etc etc) that it completely destroys their mental health and social life. Someone who can't go 10 minutes without thinking about their obsession and crying silently to themselves. These types of people have had their lives taken over, so don't act surprised when you find their secret shrine at the back of their closet.
A Shackteau is a humble, weather-beaten, structurally questionable shelter located in a spectacular or highly coveted place—Wales, Jackson Hole, Sun Valley, Crested Butte, coastal Maine, the Alps—where the building itself may be worth almost nothing, but the dirt, view, access, and mythology make it absurdly valuable.
In use:
Shackteâu - We thought it was an abandoned shed until the realtor called it a rare alpine Shackteâu with unobstructed views and listed it for $2 million.