Wikipedia
The boom-ba (Anglicized from Deitsch "Boomba," meaning "bomb") is a type of bladder fiddle, known throughout the Pennsylvania Dutch culture of eastern Pennsylvania, United States. The instrument focuses heavily on loud percussion, typically consisting of a variety of percussion instruments attached to a wooden pole. The exact designs of a boom-ba vary, with much emphasis being put on the personalization of the boom-ba. Common features typically include a spring-loaded rubber base (much like a pogo stick), with percussion instruments such as bells and wood blocks attached. Nearly all boom-bas also include a set of cymbals which crash as the boom-ba is bounced, and a tambourine which can be played with a drumstick or shaken as the boom-ba is played.
The boom-ba is similar in nature to the "stumpf fiddle", though the stumpf fiddle generally lacks the loud crashing cymbal on top. It is this loud crash when bounced that makes the boom-ba distinct.