Haha, if my kid was screaming, they would get a smack on the mouth and told "NO! Nobody wants to hear you scream". If they were wriggling around and wouldn't stop, a smack on the butt and a "I said, sit still!" always worked, at least until the learned the "I swear, kid, if you embarrass me for One More Second in this restaurant..." death stare. If neither of these things worked, we would be away from the table and into the bathroom or car in a heartbeat, and trust be, it wouldn't be a pleasant "this is rewarding the behavior because this is what my kid wanted in the first place" kind of moment. My kids learned early on that they had two choices - to behave within the parameters of what their age group could reasonably be expected to handle, or face the wrath of a very cranky mommy. I decided from the start that I wasn't interested in being the good guy or the friend, and being the mean mom who expected her kids to behave was perfectly acceptable. There was never any walking the kid around the lobby of the restaurant or letting them run around outside to blow off energy. It was a choice of either sit and behave or you won't like the alternative.
Somehow, my kids have grown up to be the kind of kids that people enjoy being around. Most of the time....LOL
**as always, here is the call out that my kids are not special needs and very capable of behaving themselves while we eat, no matter where it happens to be.