Social proof is a studied, verified effect, where people's opinions are shaped by the opinions of others at a subconscious level.

Do you hate laugh tracks? Me too. But research shows that people think shows are funnier with the laugh track than without, even if they say they hated the laugh track.

Are you annoyed by every brand saying they're "The Leading X" or "The Number 1 Y"? Me too. But marketing which includes these claims leads to higher sales than marketing without.

When I was a sales puke, I applied this principle to selling add-on insurance for car rentals. I identified a point in my pitch where I could add the words, "almost everybody takes the package". That's all, that's it. In the week when I first applied it, it added almost 10% to my rate of sale and the improvement persisted when I retained those words.

And I was dealing with all walks of life. Holiday makers of all kinds. From backpackers, to CEOs of german industrial giants, to law-school professors from leading US universities, they were all affected by the truthful claim that almost everybody bought the package from me.

Social proof works.