Rock-breaking joke

A very strict instructor is training some new recruits. He had never seen them before, so he said at the beginning, "My name is Stone, so do as I say, or you will ask for trouble.". Don't try to play any tricks with me, we will get along well. " Then he went up to each soldier and asked their names. "Speak louder so that everyone can understand." He said, "Don't forget to call me' sir'."

Then, every soldier reported his name to him until he came to the last soldier, and he began to keep silent. Captain Si Tong shouted to him, "I ask you a question, and you must answer it!" Let me ask you again, what's your name? Soldier. "He said nervously," my name is stone crusher, sir. "