An old Souther planter goes into the hospital and is informed by the doctor that his condition is pretty serious. In fact, he's going to require a heart transplant.
"Well, doctor," drawls the planter, "you'd best get on with it. But whatever you do, just don't give me the heart of a black man."
When he comes out of the anaesthetic, the doctor is leaning over his bedside anxiously. "Cal," he says, "I got to use a black man's heart." Cal pales. "But the good news is: your dick is three inches longer.