A bobber, originally called a bob-job from the 1930s through 1990s, is a style of custom motorcycle. The typical construction includes removing the front fender, shortening the rear fender, which is "bobbed" (as in bob-tail), and stripping excess bodywork as well as all superfluous parts to reduce weight.[1][2]
The bobber is, far and away, the coolest style of custom motorcycle on the planet.