When a female lands on her vagina hard thus "duffing" it up
Dude did you see that girl do a mis-vault?, it was a right muffleduff
by Liam Mason February 04, 2008
someone who lives up to every stereotype that is connected to his ethnic background. his actions make people from his ethnicity resent him and their own ethnicity.
That Jewish guy keeps complaining he makes me resent Jews even though I am one... He is such a muffleduff!
by oohree January 20, 2009