DUFF 

A term that was popular in the early 2000's and is an acronym for "designated ugly fat friend." In modern day, this term is only used by douches who can't keep up with current slang, and by stupid ass middle schoolers who think they are the shit because of the 2015 movie of the same title that attempted to resurrect the term and make it "cool."

Stupid Person 1: Why is that ugly bitch hanging out with those hot girls?
Stupid Person 2: She must be the DUFF.

DUFF by yoloswagturnupyoo February 27, 2015

DUFF 

Designated Ugly Fat Friend
The DUFF isn't always ugly or fat, the DUFF is the least attractive friend ( They can still be pretty but not as pretty as the friends) in the group which makes the others look more attractive. The DUFF is the approachable friend in the group who gives intel about the more attractive friends.

"wow i didn't know they knew each other, why is she hanging out with them".
"She's their DUFF of course".
"Oh right yeah i see it".

DUFF by MusicDream April 3, 2015

Duff 

to throw a severe beating to another person or group. Used with mal intent or to beat the ass's of.

"If you don't shut the fuck up, i'm gunna duff your dumb ass"

Duff by DamionFK December 3, 2006

duff 

the type of beer Homer Simpson drinks

pass me another Duff Mo

duff by :o) April 25, 2003

duff 

Designated Ugly Fat Friend

Two hot chicks at a bar will have a really nasty fat ugly bitch hanging out with them, refered to as a "DUFF".

"Wow that fat DUFF is hanging out with those two attractive ladies, too bad."

duff by Cobra January 26, 2003

DUFF 

Designated, Ugly, Fat, Friend - this is a person in a friend group who is there to make everyone else look good.

girl 1: she doesn’t fit in with that friend group!
girl 2: yeah because she’s the duff!

DUFF by Thatsmarthighschoolgal November 24, 2019

DUFF 

Designated Ugly Fat Friend

Doesn't necessarily have to be fat, or ugly, but is less attractive than the friends she/he hangs out with. Men/woman usually befriend a duff to get closer to his/her friends. A duff mainly gets used for info and or help, and is often lead on mistakenly or purposely. Do not allow the duff to realize who he/she is and why you are using them, because you will 100% lose them as a friend. If you even care.

Guy 1: "Hey see those hot chicks? Except that one, she's so the duff."
Guy 2: "Yah man? Let's try to be her friend, maybe get some info on her hot friends"
Guy 1: "let's do it!"

DUFF by That1DUFF November 20, 2015