Robert,
I go over this in the download. But if you're really worried about it, one thing to do is reach in the pack and give them another cookie as soon as the trick is done. That way they have a cookie. And if you're REALLY concerned you can even switch the bite cookie for a normal cookie as you're reaching in the pack to give them one, so that way if they say "let me see yours" you can give it to them, too.
But ultimately this is a larger issue of audience management. You don't have to do what everybody says or wants; you're the one performing!