Well, a stick or rigid object is threaded into the left hand sleeve of a coat which is buttoned up tightly so the left hand sleeve stands out parallel to the ground and at right angles to the body. The coat has a handkerchief in the top pocket.
Now the left arm slips down into the trousers, which must have buttoned flies and rests behind the region of the flies. The right arm is placed in the jacket sleeve in the normal manner, holding a violin bow or stick to represent a violin bow and when the music starts, the violin bow flows across the left arm as in playing a violin.
After about 3mins, the one armed fiddler starts to perspire and wants to mop his brow with the handkerchief which is in his top pocket, but he has only his right hand which is holding the violin bow. A finger of his left hand now pops out of his flies and the violin bow is passed to his penis(finger) to hold, whilst he takes out the handkerchief and mops his brow. Looks to the audience like his penis is holding the violin bow�..laughter etc.
Did this many years ago at the Royal Sussex County Hospital and one nurse in the front row fainted.