The phrase is used to mean “How is this relevant to the conversation?”, especially if a person seems to be actively avoiding the topic being discussed.
Me: Hey, do you have that $20 bucks you owe me.
Him: Hey, have you seen the movie Hot Tub Time Machine yet?.
Me: What's that got to do with the price of cheese in China?
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 $2million.