Fucking my family paradox, The theory you can never get too close to someone who is having sex with a member of your family because of the expected akwardness. Also can be used as fucking my sister paradox or fucking my mother paradox.
Friend 1: My Sister's boyfriend keeps trying to be my best friend.

Friend 2: So what's wrong with that?

Friend 1: FMF paradox man, it's too awkward.
by Billy Mcgee February 19, 2014