The toothbrush mustache is a style of mustache in which the sides are vertical (or nearly so), often approximating the width of the nose and visually resembling the bristles on a toothbrush. First becoming popular in the United States in the late 19th century, it later spread to Germany and elsewhere. Comedians such as Charlie Chaplin and Oliver Hardy popularized it, reaching its heyday during the interwar years. English comic actor Charlie Chaplin was one of the most famous wearers of the toothbrush style. Shortly after wearing a full mustache for his 1914 film debut (Making a Living for Southern California's Keystone Studios), he sported a prop toothbrush mustache for his first film as the Tramp, Mabel's Strange Predicament (though Kid Auto Races at Venice was the first released).

Source: Wikipedia