In a train in England, a band of merry men decided to trap one of their friends with a simple breath tester. To give an example, an accomplice shows the operation of this device by blowing into it, but it blocks a small hole with his finger discreetly. When the "victim" is used in turn, it does not block the small hole and blows with all his might on the advice of his friends. He then takes a big fat flour spray in the face. This old joke corn mill apparently still works pretty well, for the enjoyment of other passengers on the train.