I'll speak for myself, but there's a lot of humor to be found in sarcasm and darkness. You talk to any paramedic, they survive by developing a pretty off-kilter sense of humor.

This quote means that people can find humor in dark and sarcastic comments, and that this is something people – like paramedics – often use as a coping mechanism for difficult situations. Paramedics have to deal with difficult, sometimes tragic, emergencies on an ongoing basis, and in order to cope with their work they have developed a unique sense of humour that is based on sarcasm and wit. This helps make the difficult times less unbearable.