(Da Ugly Fucking Friend) A term to describe the less attractive females another female will have in company to make her seem more attractive or just a less attractive friend to more attractive female. (Originating in Bear, Delaware)
Jon: "Hey! did you see that girl that just walked by?"

Brandon: "Which one?"

Jon: "The one in the middle bro!"

Brandon: "Oh yeah, but she's only a 6 on a scale of 1-10 without those DUFFs."

Jon: "Yeah her other friends were pretty ugly."
by Boogey Man Brown October 5, 2011
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When a woman has been fertilised by a man. I.e she is pregnant
by Johan Forssander March 3, 2004
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Timmy: Chelsey and sarah are so hot. why does she hang around with heather. she is so fat.
Bryan: Heather is their DUFF to make them look better
by shortman94 March 30, 2010
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DUFF stands for: designated ugly fat friend. A DUFF is typically hanging around the group of pretty, superficial babes. People who see the DUFF usually wonders why she is being seen with such hot chicks. DUFFs never get ass. DUFFs have never had a boyfriend. And DUFFs spend their friday nights masterbating.
Tammy is such a prep.
DANG, Felicia is looking fine tonight.
Lorena adds that latina spice to the group.
Erica is a hot cheerleader.
and then theres Marissa.
Well, every group of girls has to have their DUFF...
by jOCKIN ON YO December 16, 2007
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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.
by Oreck December 24, 2005
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Duff
1. The type of Beer (Homer Simpson) drinks.
2.The ugly girl that hangs out with the good looking girl.
3. Also used for the gun butting move in the XBOX game Halo.
1.Homer drinks alot of Duff.
2.Man that duff is making her look better.
3. Oh shit man u got duffed.
by Jeff October 22, 2004
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"I'm glad you invited those girls, but why'd you invite the Duff?!"
by Lauren and Lesley June 14, 2007
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