The arrogant chef

I was trying not to laugh when it happened. We were inside the kitchen. I was slicing mushrooms that time when our professor/chef approached and asked me what the hell was I doing. He was referring to the way I was slicing the mushrooms. He then asked me where I learned how to slice like that. I quickly answered that the other chef/professor taught us to slice mushrooms like that. That other chef/professor told me to clench my fist a little bit so that I can protect my fingers from being cut. He quickly said that it was the wrong way of doing it and that he will show me the right way. He wanted me not to clench my fist. I wanted to tell him that I think it's kind of dangerous to expose his finger while cutting since its like the edge of the knife is running after his fingers. I thought it would anger him if I said that so I decided to keep it to myself. I was doing my own thing when my one classmates approached and asked the professor. At that time the professor was slicing something. He arrogantly turned his head around and conversed with my classmate while slicing onions. After a few seconds, we heard a sound of pain. He cut his thumb. He quickly ran out of the kitchen like a little girl. After that, the stewards/helpers rushed in the kitchen to see what happened. We all saw half of his thumb that he left behind. The stewards were all laughing and they even pasted it on the board for everyone to see. The professor came back after a week and said that he was careless that's why it happened. I wanted to butt in and tell him that it was his arrogance that made it happen. If he had stopped from slicing the onion while talking to my classmate, that accident would not have happened.