narb is, of course, bran backwards. "Bran" means "the fair-haired one" in old Irish, and was also the dog of Cuchulainn. "Cuchulainn" means "the hound of Culann", so - bear with me here - Bran was the dog of the hound of Culann.
n. An item of personal information posted online, particularly as it contributes, often unwittingly, to a personal narrative that individual is creating online. Also: NARB. (Narrative + bit.) - Word Spy