[from an old doctor's office joke about a patient with a trivial complaint] Stock response to a user complaint. “When I type control-S, the whole system comes to a halt for thirty seconds.” “Don't do that, then!” (or “So don't do that!”). Compare RTFM.

Here's a classic example of “Don't do that then!” from Neal Stephenson's In The Beginning Was The Command Line. A friend of his built a network with a load of Macs and a few high-powered database servers. He found that from time to time the whole network would lock up for no apparent reason. The problem was eventually tracked down to MacOS's cooperative multitasking: when a user held down the mouse button for too long, the network stack wouldn't get a chance to run...