From the ArcaMax Publishing, Jokes Newsletter:
http://www.arcamax.com/news/jokes/s-385767-484631
It had been snowing for hours when an announcement came over the high
school intercom: "Will the students who are parked on University Drive
please move their cars so that we may begin plowing."
Twenty minutes later there was another announcement: "Will the twelve
hundred students who went to move 26 cars, return to class."