A normal to mildly attractive looking girl who has spent so much time with a DUFF she has taken on DUFF qualities (i.e. sitting around on her ass all the time, extreme sarcasm, increased appetite, and bitchiness). Occasionally refered to as a DUFF Ass.
"Dude, that girl was pretty nice when I got here, but now she's a total DUFF Associate. I'm gonna bang her friend instead."