Some pretty good ones here. I don't spend much time out front, I get paid to work on guns, not sell them, so I don't get to hear a lot of what's posted.
But, I still get some good ones. When you're handed the phone, and the first thing said is: "can you put a gun together even if you didn't take it apart?", you're about to get a gun in a bag. Or, they bring it in and tell you it worked fine, and they cleaned it, and now it doesn't work. Did you take it apart? No, I just cleaned best I could. Well, this spot right here used to have "xxxx" mounted in it, which is now missing. This part will not come out by itself. Are sure somebody didn't take it apart? OK, I took it apart. Well, go back to where you took it apart, and if you can find the part, I won't have to order a replacement. Often, the gun has been taken apart and put back together wrong, or has been forced apart. I recently had an 1897 Winchester takedown come in for cleaning and cowboy action work, the owner had just purchased it from a friend. It wouldn't break down. Turned out, somebody had stripped the interrupted threads on the magazine tube, and simply epoxied it in place. Or, "it's been a great gun for the last 20 yrs, but then it turned into a pos." Duck gun, been used as a boat paddle an unknown number of times in the last two decades. Oh, hasn't been cleaned once the entire time. Open it up, the inside has to be scraped first so it can be cleaned. Got a pile of dirt roughly 2" tall maybe 3" in diameter. Remington 1100. No wonder it doesn't work.
Of course, the occasional request to make something full auto. Got a guy last week followed me out the door, I was going out back to test fire a gun, he wants to discreetly ask me if I can build him a suppressor. I explain yes, I can, and yes, they are legal (we are an /07 Sot).
It never ends, but at least it's entertaining.