Pictured below is Coma-Doof Warrior, a character in the movie Mad Max: Fury Road. He's noted for his fire-spitting guitar and wearing his dead mother's face as a mask.
Naturally, Make contributor Caleb Kraft wants a flamethrowing musical instrument. But he prefers the ukulele to the guitar, and so built one. You can watch a step-by-step video describing how to make your own here.
Kraft notes that his design could be scaled up to a guitar or any other stringed instrument. I suggest going all the way with a flamethrower octobasse, which is a 12-foot tall fiddle.