We use the words “Strike 1, Strike 2, Strike 3 YOU’RE OUT!” to signal warnings about poor behavior.
We usually use this technique at the dinner table, but have used it before in other places. Its particularly helpful in public places where reverence or quietness is expected (church, library, etc). When you spot misbehavior in these places all you need to do is lock eyes, put on your most stern no-no face, and hold up one finger. If the child is familiar with the Strike 1, 2, 3 reminders, they will understand this cue and “hopefully” wise up.