Desi formula of the drill master

Usually the Drill master is the equivalent of a police inspector in a school. He is a very important member of the school faculty. In fact the physical training drill during morning assemblies play an important role in refining the students, taming them and making them obedient to their teachers. But strictness beyond a limit becomes counter productive. It is well known that if nuts are overightened, they tend to become free.
Probably it was the month of July. The summer heat of Delhi in this month is oppressive to say the least. On one such hot and sultry Saturday morning the physical training session went on for a little too long. After the prayers all other members of the teaching staff went into the main building while the PT master was hell bent on delivering his duties worth all his annual salary in a single day.
The physical torture seemed endless. The children got thoroughly drenched in their white uniforms. Their patience was exhausting at a very fast rate. After a set of arm raising and clapping exercises there came the turn of bending forward while sitting cross legged. The children had to place their palms on their head and bend forward almost touching their forhead to the ground. As a voice of protest they started making a "hummmm....." kind of sound while bending. The collective sound became fairly loud and funny. Each time when the turn of bending came the sound became louder than the previous occasion. Those were the moments of both fun and dread. While all enjoyed the voice of dissent none wanted to be punished.
The master got pushed into a very awkward situation. If he ignored the revolt his reputation as a disciplinary icon of the school could get a beating. While on the other hand there was no way of finding out the leaders of the mutiny.
Ultimately he resorted to the Desi formula. He gave a sound thrashing to a few boys in the front row without asking for any explaination. "The humm...... " stopped instantly and the revolt got suppressed successfully.