During the French revolution, an aristocrat was placed in the guillotine. He looked upwards and said, "Hey! Is this thing safe?" This is an often-quoted example of gallows humor.
Laughing in the face of danger is a very human response. You are likely to hear gallows humor among transplant candidates and recipients. I always make sure that my bellboy is working before a holiday weekend. This type of sardonic wit can help to relieve the tension for some. Within the bounds of social acceptability, gallows humor can help some to deal with the strain of awaiting transplant.