Tis the season to get sick

I was out driving around today and couldn't help noticing this new trend.
If you're really cool, you apparently wander around in 30 degree weather in lightweight clothing.
Like the kid I saw going into the mall wearing just a polo shirt. He was all hunched over like he was freezing, but he's wearing this thin shirt. Then I'm driving down Noble on the way home and there's a woman standing talking to another woman. She's wearning a t-shirt. And she's got her arms wrapped around her like she's freezing.
Am I missing something here? Is it really cool to have a case of walking pneumonia, or what?