I have a friend Brian in Minnesota who was in an accident when he was ten and has since been in a wheel chair. Brian has been an inspiration in the way he's dealt with things, refusing to let his misfortune alter his positive outlook on the world, or keep him from pursuing his dreams - in high school he excelled in the directing arena of our school's theatre department, and now works for a prestigious Minneapolis theatre.
Brian has also developed an earnest and sometimes scathing sense of humor about his situation. It's a way of keeping him positive, but at the same time, his humor delicately toes the line between hilarious and uncomfortable to those who hear it, depending on how well one knows him. Like the time in a theatre meeting when someone commented that they'd been sitting so long that their lower extremities had fallen asleep.
"I can't even feel my legs," said the unsuspecting person.
"Funny," responded Brian. "I can't feel mine, either."
There was an excruciating silence, then about half the people there (those who knew Brian) started laughing. The other half (including the guy whose legs had fallen asleep) remained very uncomfortable for quite some time. It's dark, dark humor, but the decision is yours whether or not to be offended, because it comes from someone who truly knows what they're joking about.