An Australian colloquialism; describing someone intellectually impaired or moronic.
In the case of this phrase, the term "roo" is an abbreviation for kangaroo, an Australian marsupial.
Used emphatically, the phrase is sometimes amended to "a few roosloose in the top paddock".
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.