Worst thing I ever heard was at Geauga Lake when it changed over in May of 2004. I was strapped in on Dominator and we weren't moving. One of the ride ops asked the girl working the control what the hold up was. The response from her was awseome.
"I don't know where the other train is?!"
Not exactly what you want to hear, but I did offer up that it was most likely on the mid course breaks, which is was.