One who comes and visits you in the middle of the night. Just as you're about to fall asleep he sprinkles his dirty dust in your eye and precedes to have anal intercourse with you until you drift off to sleep in a pleasurable manner.
"Dude what's thatin your eye?"
"Oh it's just dirty dust, the Dirty Night Night Fairy came and got me last night just before I fell asleep."
"Nice bro, dirty dust for life."