I think this is one of my favorite idea. Children think of everything as a competition, so by allowing them to see the good behavior of their peers would make them tighten up. I think this idea is a clear Way to let the kids know when to stop and what is going to happen if they don't.
For the Kid Who Blurts Out Talkin Token behavior intervention: Give a student 1-3 tokens during a whole class discussion. Each time the student participates (or blurts out) they hand over a token. Once they're out, they're out! If they are doing exception