The Joke That Almost Backfired

We played many jokes on Mr. Yonce, my Senior English teacher at Highlands High School (like the time we turned his car's license plates around so the backs showed). However, one of our jokes was so successful, Mr. Yonce almost flunked our class. 
 

We had Mr. Yonce for fourth period. This is lunch time. We would have class for about 20 minutes, go to lunch, then return for the remainder of the period (fourth period was 30 minutes longer than the others so the classes could stagger for lunch). Mr. Yonce was no dummy. He always locked the classroom door when we left for lunch.One day, about one month before graduation, the door didn't latch. 

Several of us noticed this at once, and we decided to forego the marvels of the cafeteria. Instead, we waited for Mr. Yonce to leave, entered the room, and tried to decide what to do. We decided to rotate the room 180 degrees. I don't mean simply turning the desks around. I mean moving desks, bookshelves, lecterns, wastebaskets, etc. to the other side of the room. When we were finished, the floorplan looked like someone picked up the room, and turned it around. 

As the others returned we sat in our desks, and waited for Mr. Yonce. When he came in he blew up. He ranted. He raved. He said he was going to flunk all of us, and then called the principle, Mr. Schwinn, on the intercom. 

Flunk us? Say, "Huh? You can't flunk us!" 

"Oh, yes I can. Just watch." 

You see, the problem was that to graduate, one needed 18 credits. Most people graduated with 21, so this wasn't much of a problem. The problem we now faced was that four of those 18 credits had to be English credits. All of us in the class were pretty standard -- we took one English course per year. Therefore, we needed to pass Senior English in order to graduate in one month! 

What could we do? We pleaded to no avail. Mr. Schwinn and our doom approached swiftly. We all concluded that our parents would simply kill us, and our pain would soon be over. We heard Mr. Schwinn's footsteps in the hallway. 

Silence in the room. Mr. Yonce had a smile on his face. (He gloated well. I've always wanted to gloat the way he did, but I've never mastered the skill as well as he.) Mr. Schwinn enters the room. 

Mr. Schwinn breaks up in laughter. He laughed so hard that he fell against the door frame. Mr. Yonce's mouth fell open for a moment, turns toward us, and says, very slowly, "Put - it - back."