When I was in college, our Math professor always had the habit of putting his wristwatch on his desk and checking it from time to time to see how much time is left till the end of class. The math class was quite boring, but worse than that was the prof’s way of speaking – he had a very monotone voice and we were getting pretty sleepy by the end of his lectures. On a Friday, when his class was the last on the schedule, we were dying to go home, but couldn’t – he was quite strict and would not allow us to go home earlier. But we found a solution ;)
Our best math student, John H, was sitting in the first row, right next to the professor’s desk. We quietly asked him to give us the prof’s watch. He whispered that we are crazy and that he wouldn’t do it. As we were quite determined to get the watch, we finally made John steal it from the prof’s desk and pass it on to us. Very quickly, we set the time ahead by 20 minutes, gave the watch to Johnny and he put it back – while the prof was writing something on the whiteboard. When he checked the time again, he didn’t suspect anything – he just said that we have 10 more minutes till the end of class… When we got out of the classroom, there was nobody in the hallways – other students were still having classes, but we quickly left the building, before the prof could realize that we pulled a good one on him. Long time after that, we still were laughing our ass off at this prank.