I used to like reasoning with them.
I would insure them that I did not feel obligated to pay them jack squat, and that since they bought the debt of a dead beat what did they expect. Then they would plead with me, to get me to pay them. I would then tell them that I bet if they asked nice, Macy's will give them their money back. Then there would be a long awkward pause, then I would bust out laughing and say... "Nah, I'm just kidding they'll probably laugh at you too".