A bowler hat is a hat made around the mid to late 19th century in London. It has a rounded top and a curled brim. In America it is known as a "derby" due to the name of the man who made it popular, Edward Smith-Stanley, 12th Earl of Derby. The hat was very popular around 1880, but since then it's use has slowly declined. In 1960 people decided they were out of fashion, and now they are rarely seen in public. Although once in a while a tendy young upstart can still be seen sporting this retro hat as a way to look different.
Guy-1: Hey, that girl who just walked past was wearing a weird hat. I wonder what it's called.
History-slug: Why that, my good fellow, is a bowler hat.
Guy-1: HOLY SHIT A TALKING SLUG! (dies of a heart attack).
History-slug: Remember kids, always tip your hat when walking past a lady acquaintance.