A popular substitution for "bloody hell", "god dammit, or "motherfucker" used when faced with a particularly troublesome or preposterous obstacle. A reference to one of the curses in Game of Thrones. You can tell whoever uses this term probably needs to stop watching Game of Thrones and go outside more.

when you've done something so cringe you can't stop replaying it in your head and it stops you from getting on with your every day life