A
duck off is a girl/boy who is used for forms of sex in private but is rejected in public.
Some may be considered 'sluts' while others are average
girls. Only about half of them actually know that they are
duck offs.
Sam:She's
beautiful, are they dating?
Jordan: No way, she's just his
duck off.
Sam: Well I can't say much, I've been the
duck off before.
Jordan: Me too girl.