When someone befriends the handicapped solely based on the fact that they have a disability. The Duffy Effect involves a person who does not take into consideration that their new handicapped friend may actually be undeserving of friendship.
Katie: "I've always been nice to Ryan, but now he asked me to prom!"
Drew: "The handicapped kid? This is a textbook example of The Duffy Effect! That kid is an asshole anyway."