Duff 

1. The other friend who blends in the background

2. To TRY copy someones lifestyle

Duff: John dats a cool new haircut
John: Thanks you gay

2 days later...

Duff: John i got ur cool new haircut

Duff by M15A April 11, 2008

duff 

Designated ugly fat friend. The girl (or guy) in a circle of friends who is usually the least attractive in the group. Usually the one who provided the ride, designated friver or paid cover charge for the others.

Kim on Moesha is the DUFF.

duff by xzybit December 28, 2005

Duff 

drop kick

jake is a duff

Duff by suwoop234 March 30, 2011

duff 

British pudding

What ho, pip pip, my dear chaps and chapesses. I think I'll have some scrum-tiddly-umptious plum duff. Good show!

duff by SvenTheBold February 28, 2015

duff 

v. to duff - to fart

n. a fart

Origin- 20th Century, British Columbia, Canada round about Pavilion, B.C.

Oh, did you duff?

That's was a really ripe duff.

duff by MJD June 3, 2004

duff 

to beat up, to fight with and win.

I'm gonna duff you up!

duff by frank April 23, 2003

duff 

used as an adjective or a noun. means cool, awesome, steeze, hot, the shit, etc.

1) that kid is so duff, i want to fuck him.
2) the party last night was mad duff; everyone was there.

duff by Mahzipan September 5, 2005