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.

I only hang out with her becuase I need a D.U.F.F., otherwise, she'd be, so, history.

D.U.F.F. by B.a.m December 21, 2005

D.U.F.F. 

The Designated (/Dumb) Ugly Fat Friend.

The cock-blocking friend of the hot chick you're trying to hook up with, often the target of the wingman.

I was totally in with this chick and then her D.U.F.F. totally cock-blocked me!

-or-

I'll take her, while you distract her D.U.F.F.!

D.U.F.F. by Victory2FuManchu September 7, 2006

D.U.F.F. 

Designated Ugly Fat Friend---Usually hangs around extremely Hot girls and DUFF's usually tend to be girls themselves

Bruh do u see dat D.U.F.F. hangin wit Jennifer

D.U.F.F. by WM-Dawg March 27, 2008

D.U.F.F. 

1. Dumb Ugly Fat Fuck
2. Designated Ugly Fat Friend (the less harsh defintion)

That we-gotta-go-girl is such a D.U.F.F.

D.U.F.F. by cchriss92 August 3, 2007

D.U.F.F. 

D-dumb
U-ugly
F-fat
F-friend

or

D-dumb
U-unreasonable
F-fuck
F-face

Go with it as you wish.

Snooki: "Oh my God. What a D.U.F.F.!"
Deena: "I know, right? Totally a duff."

D.U.F.F. by Smigslovesyou101 April 13, 2011

D.U.F.F. 

Designated Ugly Fat Friend. If you know of a DUFF, You are a DUFF, or you've heard of a DUFF, you are in luck. Because I hate to break it to you but you are a DUFF. You don't have to be fat or ugly to be a DUFF. DUFF is just a catch for a person who doesn't fit in. If you ever felt left out, excluded, or just different it means you were a DUFF and potentially are one now. But don't worry. Being a DUFF is a good thing. It means you are an original person. SO pump your fist in the air if you're a DUFF!

Tyler is a D.U.F.F.

D.U.F.F. by ThtYllwBch June 9, 2015

D.U.F.F. 

Dumb Ugly Fat Friend.

Damn that bitch is a D.U.F.F. Damn your sister's hot, and who's the DUFF?

D.U.F.F. by Pwat May 2, 2006