The only thing I can think of didn't go extremely wrong, but I guess it still fits.
One time when I was 13 years old I tried to repair a pair of headphones despite having no real knowledge of how to do such a thing. It was a cheap pair of the earbud kind, and one of the wires had snapped completely. I peeled away some of the plastic exterior stuff and just kinda twisted the frayed ends of the wire together, then tested them out. Didn't think to cover them, didn't think it might be a good idea to test them while not wearing them, I just put them on and gave it a go. The exposed wires zapped my cheek and the shoddy repair didn't even work. :<