My second year high school physics teacher was a popular young man of around 23 years old. He enjoyed a joke or two and made the lessons memorable, if not fun.
When a teacher was called to an away mission, usually a phone call, it was, in those days, customary for the class cabal to appoint one of their members to keep watch at the door for the teachers return. This permitted the rest of the class the freedom to enjoy a chalk fight, or as often happened, a competition to see who could engineer the best paper glider capable of achieving escape velocity from the classroom, if not the Earth.
I remember one particular day, when the keeper of the watch, spied the teacher swiftly making his way back down the hallway toward the classroom which was in an uproar over the latest unmanned glider test flight. Suddenly the appointed stake out officer announced quite loudly, "Here it comes." The class rapidly resumed the quiet demeanour of angels in contemplation of the value of intelligent desire.
Dear teacher made his entrance with a fury and flurry not seen since the last emergency fire drill. All was quiet as he surveyed the remains of a dozen or so, test flights scattered around the test pad, also known as the floor. Then he spoke,
"Boys," he exclaimed, "Your teachers, including me, are well aware that you have nicknames for us. Indeed those of us in my profession who are not disabled by having our heads up our backsides are even amused by some of your more inventive names for us, but we really are not amused by phrases proclaiming our approach as, "Here it comes." In future, you would be best advised to reserve that phrase for your personal activities in the privacy of your bedrooms. I can assure you all that I am not an it."
The cheers emanating from the collective young test pilots were very encouraging and the teacher laughed with the rest of us.