Gus Johnson is a YouTube comedian with a short rap about pretty much anything you can think of. In this one, he looks at the campus phenomenon of that guy who never wears a jacket. You've seen him around, although it's more common in high school, as far as I can tell.
My kids, and all the kids I knew, went to high school all winter without coats (although most would wear a sweater or hoodie). They said it was because there are no coat hooks in their huge school, and people would steal a coat even if there were. Lockers are too small for winter coats, and security rules prohibit students from wearing coats in class. A story from opie2 gives us another reason.
I teach middle school. One day a 12-year old boy shows up in my classroom at 8:00 in the morning dressed in a t-shirt, shorts, and flip- flops. It's about 45F outside. He stands there with his teeth chattering, shivering like a leaf in the wind.
Me: Dude, you're cold because you're not dressed properly. You need pants, long sleeves, socks and shoes, and a jacket.
Kid: That's exactly what my mom said to me this morning.
Me: Well why don't you listen to her?
Kid: Because I can't let her win.
The jacketless guy on campus may be simply retaining his earlier habits, and might learn his lesson eventually as he trudges several blocks between each class on winter days. Unless he's just too high. -via reddit