Initialism for 'I don't give a fuck I'm Snoop Doggie Dog', a line from the song 'Vato', by popularrapper Snoop Dogg, used to express a complete lack of interest.
Mark: 'Guess what, my brother just won the Superbowl!'
Simon: 'IdgafISDD.'
A religion full of people who simply don't give a fuck about anything. you should totally convert to Idgafism, it's the only religion that actually means anything.
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.