An old person between the age of 50 and 75 who doesn't realize what impact their grumpy mood has on the people around them.
For example the scene from A Million Ways to Die in The West, featuring the main characters father sitting in a rocking chair. The father is a Needle Shits Old Fart!
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.