I had one where I still can't figure out how it happened.
I was at anindoor flea market, plugging in an old portable record player. It didn't do anything, so I touched the small connector where the cord went into the player (similar to the well-known figure 8 connector) and immediately got bit! Even though I was standing on a wood floor with rubber soles on my shoes it hurt pretty bad.
Yet when I thoroughly tested that cord later I never managed to find a fault.
