Something that takes longer than expected. The term is a reference to Gilligan's Island, in which the characters take off for a 3 hour tour but end up stranded on an island.
"How was your bike ride?"
"Sucked, it ended up being a three hour tour after John lost the map"
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.