How did the policeman discover that the whole thing was a joke?
It has never been explained why university students seem to enjoy practical jokes more than else. Students specialize in a particular type of practical joke: the hoax. Inviting the fire brigade to put out a nonexistent fire is a crude form of deception which no self-respecting student would ever indulge in. Students often create amusing situations which are funny to everyone except the victims.
When a student recently saw two workmen using a pneumatic drill outside his university, he immediately telephoned the police and informed them that two students dressed up as workmen were tearing up the road with a pneumatic drill. As soon as he had hung up, he went over to the workmen and told them that if a policeman ordered them to go away, they were not take him seriously. He added that a student had dressed up as a policeman and was playing all sorts of silly jokes on people. Both the police and the workmen were grateful to the student for this piece of advance information.
The student did in an archway nearby where he could watch and hear everything that went on. Sure enough, a policeman arrived on the scene and politely asked the workmen to go away. When he received a very rude reply from one of the workmen. He threatened to remove them by force. The workmen told him to do as he pleased and the policeman telephoned for help. Shortly afterwards, four more policemen arrived and remonstrated with the workmen. As the men refused to stop working, the police attempted to seize the pneumatic drill. The workmen struggled fiercely and one of them lost his temper. He threatened to call the police. At this, the police pointed out ironically that this would hardly be necessary as the men were already under arrest. Pretending to speak seriously, one of the workmen asked if he might make a telephone call before being taken to the station. Permission was granted and a policeman accompanied him to a pay phone. Only when he saw that the man was actually telephoning the police did he realize that they had all been the victims of a hoax.