Yet another Australian expression of surprise, disbelief ar anguish. There is quite a collection of these (see tags below).
Usually said with each word pronounced very separately and deliberately, but is quite often uncontrolled. The first thing I said when I turned on the TV and saw the World Trade Centre collapse was:
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.