If you do live demos for a living, you develop a very specific kind of nervous system. Here's what I've learned to make peace with.

Rules I Live By

• The demo gods are real and they are petty. The one API call you didn't test is the one that times out on screen.
• Always have a recorded fallback. Not because you'll use it, but because having it is the only thing that lets you not need it.
• Narrate the failure. When something breaks live, explaining what's happening is more impressive than a flawless run. People trust the person who stays calm.

The job is basically "read the docs so the customer doesn't have to," and then perform that knowledge under mild duress. Somehow I turned that into a career. No regrets.