How to make a class quiet during lecture trick

We as students have much to discuss with our friends in the classroom and that too while the teacher is giving their lecture. And also this also depends on how much boredom the lecture is. I’m sure we won’t be discussing about any rocket science or about nations economic growth, rather it is going to be the gossips of a girl around you and your favorite hero's latest adventure. This will definitely annoy the teacher as it disturbs the lecture as they will be in a hurry to rush up the portions before the deadline and so they react to it.

It is okay if one or two student talks, what if the whole class thinks of their hero and girls? Then the whole class is going to be a fish market (which is the word teachers used for describing a talkative class).  Different teachers handle this situation differently.

But one of my teachers had a different solution. This happened during some random semester of engineering. Whenever the professor turns to write on the board the negotiation sound in the fish market increased. When he turns towards the class the market was silent. This silence remained only until the teacher is facing towards the class and again negotiation starts when he turns towards the board. This went like two/ three times and professor got irritated. Now he turned back to the class and said “if you allow me finish the lecture, I will allow to speak for some time"

 Guess what? The whole class remained silent for the next of the session. Now he finished that boredom topic and said you can talk now till the class finish. To the surprise no one spoke during the talking hours, then as the teacher is standing in the dais and facing the class. He was like, class I gave you time to talk and what now, no one have anything to speak?