My stupid boss
He was a nice guy but ignorant as H***. He had been an auto mechanic and after he had a heart attack and a triple bypass he continued smoking. His heart attack had been brought on by carbon monoxide from the fumes off of car engines. I pointed out to him that cigarettes had carbon monoxide but he said it wasn't the same kind of carbon monoxide.
I was working for him in the warehouse and I had to pick something up and bring it back so after he lit a cigarette I left. It took about an hour to get back and when I did there he was sitting in his chair dead. I called 911 and of course our manager and sure enough, he was very dead.
I didn't freak out but this affected me for years and to this day the mental image of him dead of a heart attack still haunts me to this day. I'm retired and this was 41 years ago.