dark side of the moon

The ass hair around one's lower buttocks and buttcrack that is visible to an individual being mooned while looking up from a lower elevation than the mooner. Often times, the dark side of the moon is used from 2rd floor windows or higher in Apartments or Dorms for full effect.

"Hey, is that Kevin down in the street?" "Hell yeah!- He's fixing to see the dark side of the moon!"