Acronym for Designated Ugly Fat Friend, the person in a group of men or women who is clearly perceived to be least physically attractive person.

They may be genuine friends with other members of the group, or may just be there through design, for example:

  • To make the group appear charitable
  • To act as a source for favours
  • To play the role of a confederate when the group meets members of the opposite sex (assuming that if a guy is nice to the DUFF, then he will be nice to the cool chick)
  • To attend a cool girl's blind date for security purposes