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21. duff
n. an inert substance used to dilute a narcotic such as cocaine.

The substance must be similar in appearance to the narcotic so as to satisfy the suspicions of the narcotic purchaser. The introduction of 'duff' to a narcotic increases the profit margin for the seller if the selling price of the product is not adjusted for the amount of duff introduced.

See also cut
"This shit isn't anything but duff!" A phrase one may use when the narcotic purchased for one's pleasure does not administer the desired effect.
1. 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."
by Cobra Jan 26, 2003 add a video
2. duff
the type of beer Homer Simpson drinks
pass me another Duff Mo
by :o) Apr 25, 2003 add a video
3. duff
Designated Ugly Fat Friend.
That 3rd girl is definitely the duff of the group.
by G Jan 2, 2004 add a video
4. duff
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 Aug 20, 2004 add a video
5. duff
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 add a video
6. duff
a teenage pop star with absolutely no talent.
hillary duff sucks
by hillary's ex Apr 12, 2004 add a video
7. duff
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.
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