When a person is not paying attention, distracted, daydreaming or considered mentally unattendant, they are usually discribed as "brain afk".
afk is an abreviation for "away from keyboard", usually used by the gaming community to indicate when a person has left their computer (e.g. to get a drink, go to the toilet etc.) and therefore unable to act in-game.
"brain afk" is meant to describe a persons mentality to (metaphorically) have left their brains temporarily, being the reason for the person to not pay attention or realize what is happening in their surroundings.
Teacher: Can someone please give me the answer to the question?
Student: What was the question? I was brainafk when the question was asked...
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.