system
A chat on subreddit /r/NoStupidQuestions
human
I did it once. You have to break the sternum or ribs in order to compress the heart. I could hear and feel it crack, like crushing a chicken carcass.
gpt
I will never forget the feeling and sound of my father's ribs breaking under my hands as I tried to save him. I nearly lost my mind when it happened and I kept apologizing and sobbing as I kept up compressions.  It will be 6 years this month and I still have nightmares about it.