Literally stands for Designated Ugly Fat Friend. This is the bitch who comes out of no where to cockblock you when you are about to get a chick home with you. She is often recognizable by her fat ass, bad hair and sour disposition. Her main goal of the night is to fend off any advances on her friend so she will have company at the diner when she is stuffing her fat face with an omelet and a side of disco fries while she bitches about anyone and everyone. The D.U.F.F can be defeated with a high level wingman, but you will be expected to return the favor; a job not for the faint of heart. A naked D.U.F.F often smells like a box of crayons.
"Dude, I was about to bag this chick, but then her army of D.U.F.F's came out of no where and pulled her away. She must be a Volleyball player!"
Standsfor:Designated Ugly Fat Friend
The Duff is the girl or boy in the friend group who is always doing there friends homework and does not have a great sense of style, probably wears alot of baggy jeans and is mostly feeling left out,every friend group has a DUFF and the Duff is not really fat just not as cute or cool as the rest of the cliqe and the DUFF has messy hair maybe short
Guy:OMG look it's them
Other guy : wait who's she
Guy: oh she's KENDALL /THE D.U.F.F
An abbreviation for 'Designated Ugly Fat Friend'. Often in many large groups of women (usually adolecents) there will be a D.U.F.F. as a means to look better by comparison.