A combination of Romantic and Dangerous, usually used to describe a potential boyfriend/girlfriend who's not ideal.
Guy 1: So I really like her, but she spent our first date talking about table settings at our wedding.
Guy 2: Sounds really romangerous, I'd stay away.
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.