How Your Lie Can Set Trends

I have this theory that certain trends take off because human courtesy validates noticeable differences. 

When I was in college, my bank teller, a larger women, sweet as can be, wore a Hawaiian flower in her hair. Every time I'd see her, she'd have a different flower. Every time I saw her I'd say a similar thing, "I like your flower." This easy compliment allowed us to have a more fun exchange as two humans in a transactional situation. Did I actually 'like' her flower? Not really. I was indifferent about the flower. What I liked about it was that it was different and it was worth saying something. Undoubtedly, I'm not the only one to have complimented her flower, which makes me believe that there is a powerful force in this human courtesy we pay to other.

The powerful force of validation likely sticks with the bank teller. I mean, all of these people say they like her flower. Why wouldn't she continue that behavior of wearing it? And she did.

This small example of human courtesy during routine friendly exchanges, I believe may be the catalyst for large trends we see play out in our culture. When everyone started shaving the sides of their heads, that was different. The people closest to these early adopters like told them that it was cool and they liked it, even if the complimenter themselves wouldn't do it. After enough validation happens and enough public display of the 'different factor', more and more people adopt the look, which then breeds more and validation from a wider group of people. Over time, enough usage happens to qualify as a trend.

In essence, what's different gets talked about to your close network, often it gets validated, even out of courtesy, not necessarily taste or personal preference. 

What trends do you think fall into this category?