Beanies were popular among schoolchildren in the early to mid-20th century. Famous science fiction author Ray Nelson made a whimsical addition to these caps with a plastic propeller attached to the crown. These propeller beanies saw a brief period of popularity before the hat eventually became associated with nerdiness, and later social awkwardness and idiocy.
Gallery
Pyro's Beanie
The Pyro from Team Fortress 2 wearing a Pyro's Beanie.
The Pyro from Team Fortress 2 wearing a Pyro's Beanie.