D.U.F.F.

The Designated (/Dumb) Ugly Fat Friend.

The cock-blocking friend of the hot chick you're trying to hook up with, often the target of the wingman.
I was totally in with this chick and then her D.U.F.F. totally cock-blocked me!

-or-

I'll take her, while you distract her D.U.F.F.!
by Victory2FuManchu September 07, 2006
Get the D.U.F.F. mug.