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51.
1.A incognito way to compliment a nice behind without being heard or looked at by the selective the female target.the term started in NJ in the summer of 2007 and is now being used by college students,frat brothers and perverts up and down the east coast!

2.Nice Big round mound of butt that defies the laws of physics.
1.Jimmy have you seen "Billy Duff"? (while pointing out a target)
2.I was strolling down the beach earlier and saw a "Duff".
3. "Duff" to the right!
4. That's quite a large "duff".
by Joemy mckenzanela November 16, 2010
1 2
 
1.
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."
by Cobra January 26, 2003
1387 307
 
2.
the type of beer Homer Simpson drinks
pass me another Duff Mo
by :o) April 25, 2003
638 235
 
3.
Designated Ugly Fat Friend.
That 3rd girl is definitely the duff of the group.
by G January 02, 2004
500 221
 
4.
A unattractive female who is always seen with another female who is marginally more attractive. It is usually impossible to score with the hotter female without the duff receiving her fair share of the action.
Damn! I so wanna tap that chick.. but goddamn, she always has that duff Nicole hanging off her. Look at that fat mess!
by Steve0 August 20, 2004
440 295
 
5.
UK usage

1) Something that's flawed or faulty

2) To duff up, to assault, beat up etc
He sold me a duff DVD so I duffed him up.
by black flag May 31, 2004
353 210
 
6.
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.
by B.a.m December 20, 2005
190 75
 
7.
marijuana that has already been run through a vaporizer at least once.
all i've got left to vaporize is some duff from last week, but we can still get pretty high.
by stoner June 18, 2006
143 73