Watching the TV while changing the strings. One time I tried doing this and I got so caught up in what I was watching that I wound the pegwinder the wrong way, tightening the string instead of loosening it. This shouldn’t be a big deal - all that will happen is that the string will break, right? - but in my case, it broke (it was an unwound string) and the end of the string went through one of my fingers and embedded its end into the fingerboard. I had to use pliers to pull it out of the board, then I had to get it out of my finger. Oh, there are all sorts of bad outcomes I can see here! But I cleaned it up as well as I could and luckily, it didn’t get infected. Guitar strings are not the world's most sterile objects, especially old ones, LOL. I’m sure there are worse stories out there, though.