I think that yes, you can find humor in about anything and that includes tragedy. Is it appropriate, probably not, but what is the alternative? Sitting around just crying all day about it?
I was in emergency services for many years, as a 911 dispatcher and also working on an ambulance and in the hospital for a bit. You'd be surprised when you are at a fatal car crash how the workers might be laughing about it the next day, or after an especially tragic 911 call where someone has been beat, there might be light banter about it. Does it make the people insensitive? Maybe, if you want to be politically correct, HOWEVER, there is no way you can immerse yourself in that job, surround yourself with tragedy and not lighten up. If you sympathize with every unconscious patient that is dying, you will crack emotionally. You don't want a Doctor that is too emotially attached to patients or else they won't make rational choices and decisions.
I remember speaking to a lady who was being shot at by her son... he ended up killing her while she was on the phone with me. Yes, it was tragic, yes it was horrid, but if I had spent time crying about it I wouldn't have been able to take the next call. It was the one and only time someone died while I was in charge of helping them. I remember the next day talking about it and having to surpress giggles, I don't think I found it funny, but I think sometime giggles or laughter is more an outlet, like a pressure valve, something is going to bust, so you let off steam, you let off emotion, and laughter is the only accepted emotion when you have a job to do. If you cry about it, you will be sent to a councelor to "deal" with it. We are emotional but we can't allow ourselves to be overwhelmed with sadness or we will have a nervous breakdown.