An expletive used by some NPCs, commonly ones residing in the major city Ul'dah, in the popular MMORPG Final Fantasy XIV. The expletive references the twin deities Nald'thal, god of death and the underworld, and patron deity of Ul'dah.
It was revealed at Fan Festival NA 2014 that the saying was created as a result of senior translator Koji Fox loving swearing, and "wanting to get as much swearing as possible".
Ul'dah Citizen: Thal's bloody balls what is that thing?!