Propeller Beanie Caps 

Beany caps were hugely popular starting around 1952 due in large to the popularity of Beany and Cecil, the animated cartoon about Capt'n Huffenpuff and his nephew, Beany Boy.  Beanie caps became de rigour with fraternities in college and even Beaver Cleaver wore one.  Beanie caps are still immediately recognized and are making a come-back.