To get your ass kicked REALLY badly. If you got "duffed", you didn't just get punched in the face, hit the floor and kicked once or twice hard... you got hit in the face, hit the ground, then got hit in the face several more times, possibly had your head bashed into the cement, got kicked in the ears, neck, kidneys and various other soft spots on your body.
"Yung, that nigga D-Set laid up in the hospital. He smoked up that whole QP he was fronted by main man and got duffed."
Duffed (v) - The act of getting used and or manipulated by an attractive, mentally unstable person of the opposite sex. Unfortunately this includes an abundance of flirting, profound mixed messages, and sexual enuendos that don't actually lead to SEX, merely the illusion that it will. The Duff usually ends by the Duff-er getting back together with their original girl/boyfriend, leaving the duff-ee with a killer case of blue balls/dry-gina.
Man, I thought this relationship was going to go somewhere, but really I was just getting Duffed!