This phrase is code for marajuana. Teenagers in japan have named it after a kid from an ancient japanese folk-tale. Penn Chan would act as though he was high all the time. The kids saw it to be a fitting code name so the phrase is now commonly used in asia and has recently spread to the states.
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.