The combination of sweat from the ballsac and anus that creates a buttery film on the grundle and butthole. occuring usually from an unwashed scrotum creating a smelly odor that worsens in thickness and odor by the minute. Also known as DB or Deeb.
duck butter is the nasty film of sweat and someother shit that builds up in a man's taint (space between balls and asshole). it got it's term because that shit is thick like butter