A former Sergeant in the Marine Corps took a new job as a High School Teacher.
Just before the school year started he injured his back and he was subsequently required to wear a plaster cast around the upper part of his body. Fortunately the cast fitted under his shirt and wasn't noticeable.
On the first day of class he found himself assigned to the toughest students in the school. The smart-aleck punks, having already heard that the new teacher was a former Marine, were leery about him and he knew that they would be testing his discipline in the classroom.
Walking confidently into the rowdy classroom the new teacher opened the window wide and sat down at his desk. When a strong breeze made his tie flap he picked up a stapler and stapled the tie to his chest.
There was dead silence...and the rest of the year went VERY smoothly!!