Okay, just how easy is it to shoot fish in a barrel? For one thing, how big is the barrel? Even if it's fairly small, fish seen from the top are edge-on. They're not very big targets, and they swim around a lot. If it's a normal-sized barrel they've got maybe a foot, foot-and-a-half radius to move in. Plus the surface of the water would make them look like they're a few inches away from where they actually are. And every shot would leave these great big ripples that would take ages to die downso you could aim again. What's more, once you started firing there would very soon be great big holes in the barrel, and then all the water would get out. It'd probably take the fish with it. Really, it'd probably be pretty hard to shoot a fish in a barrel.
Well, unless there wasn't any water and it was just full of dead fish. But then why would you be shooting them?
In other news--raise your hands. How many of you know the word "lynchpin" and what it means? Good. Now how many of you actually know why the heck it's called a lynchpin?
...That's what I thought. I not only had no idea, I never even thought to wonder about it.