A pork pie hat or porkpie hat is a type of hat made of felt or, less commonly, straw, and similar to a Trilby or a fedora but with a flat top. The crown is short and has an indentation all the way around, instead of the pinch crown typically seen on Fedoras and homburgs. The pork pie hat originated in the mid 19th century.Originally referring to a type of woman's hat, it gets its name from its resemblance to a pork pie. The pork pie hat was a staple of the British man-about-town style for many years. Robert Oppenheimer, the physicist known as the father of the atomic bomb frequently sported a pork pie hat. The May 1948 (Vol. 1 No. 1) issue of Physics Today showed a pork pie hat laid on some physics equipment, and most readers knew this was a reference to Oppenheimer. Singer Dean Martin was known to be partial to pork pie hats, and they became a trademark of the silent film comedian Buster Keaton who handmade his own, up to twelve a year.The hat was prevalent in New Guinea in January 1944, when Australian troops had just defeated a Japanese stronghold at Kankiryo Saddle. The book Australia in the War of 1939—1945 Series 1—Army Volume VI—The New Guinea Offensives (1st Edition 1961) states on page 766:According to the historian of the 2/10th Battalion, when word was received that General Vasey would visit the area on the 2nd, a signal was sent to all companies: "Other ranks will cease calling officers by their Christian names and will cease wearing pork-pie hats."Pork pie hats are often associated with jazz, blues and ska musicians and fans. Charles Mingus wrote an elegy for jazz saxophone great Lester Young called "Goodbye Pork Pie Hat". In Jamaica, the hat was popularized by the 1960s rude boy subculture, which traveled to the United Kingdom and influenced the mod and skinhead subcultures (although Jamaican and British pork pie hats are more similar to a very short-brimmed trilby rather than the US style). Jamaican ska artist Laurel Aitken devoted an entire song to the hat called "Give Me Back My Pork Pie Hat."