Duff 

Scottish slang for a vagina

Also means something is rubbish, crap or broken

I'll kick you in the duff

That's totally duff

Duff by Freakosaurus November 19, 2006

DUFF 

designated ugly fat friend.. everyone has one to make themselves appear more attractive.. mostly females.. gets on boyfriends nerves

girlfriend- "hey tony lets go to the movies tonight"
boyfriend- "ok cool"
girlfriend- "is it ok if kellie comes cuz she has no friends"
boyfriend- "no that fucking duff cant come"

DUFF by banana warrior March 29, 2009

duff 

To strike

Geoff pushed me so I duffed him in the face.

duff by ben October 6, 2003

Duff 

the act of locking the door behind you when you arrive to your place to lockout someone who may intrude or barge in unexpectedly.

"Hey did you duff the lock? Yeah man, don't worry I duffed it."

Duff by Pants007 January 20, 2009

DUFF 

Dumb Ugly Fat Friend: Usually accompied by the attractive girl that you actually want to talk to.

That girl is so hot, but she has that Duff standing next to her.

DUFF by Cody August 23, 2004

DUFF 

(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."

DUFF by Boogey Man Brown October 5, 2011

duff 

When a woman has been fertilised by a man. I.e she is pregnant

She is up the duff

duff by Johan Forssander March 3, 2004