Worst gun you've ever fired?
For me it would have to be a VZOR 70.
One of my friends brought one of these over one day when we were getting ready to shoot. The first thing I noticed was the feel of 60 grit sandpaper as I racked the slide. I disassembled the gun and noted that it had been subjected to years of neglect. I cleaned and oiled it and was able to get it to feel like 250 grit sand paper. This poor gun jammed on nearly every round that we tried to put through it.
Months later I went to the range with my friend's brother, he pulled out a VZOR 70. At first I thought it was the same gun, but the world couldn't be so lucky. This one functioned just about as well as the first. Now I'm aware that these could have been so poor strictly because of neglect, but they're just not all that pretty or comfortable either.
Hanging out at the gun store one day we were talking about that thing and the owner made the comment that it would "make a good sock gun." Meaning that it would be a great gun to drop into a sock and beat somebody over the head with.
I like to joke that these guns were formerly owned by a now dead Czech police officer, he trusted his life to them.
What's the worst thing you've ever seen / fired?